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* merged 3.0.101 tagWolfgang Wiedmeyer2015-10-221-12/+14
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* exec: do not leave bprm->interp on stackKees Cook2013-01-111-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit b66c5984017533316fd1951770302649baf1aa33 upstream. If a series of scripts are executed, each triggering module loading via unprintable bytes in the script header, kernel stack contents can leak into the command line. Normally execution of binfmt_script and binfmt_misc happens recursively. However, when modules are enabled, and unprintable bytes exist in the bprm->buf, execution will restart after attempting to load matching binfmt modules. Unfortunately, the logic in binfmt_script and binfmt_misc does not expect to get restarted. They leave bprm->interp pointing to their local stack. This means on restart bprm->interp is left pointing into unused stack memory which can then be copied into the userspace argv areas. After additional study, it seems that both recursion and restart remains the desirable way to handle exec with scripts, misc, and modules. As such, we need to protect the changes to interp. This changes the logic to require allocation for any changes to the bprm->interp. To avoid adding a new kmalloc to every exec, the default value is left as-is. Only when passing through binfmt_script or binfmt_misc does an allocation take place. For a proof of concept, see DoTest.sh from: http://www.halfdog.net/Security/2012/LinuxKernelBinfmtScriptStackDataDisclosure/ Signed-off-by: Kees Cook <keescook@chromium.org> Cc: halfdog <me@halfdog.net> Cc: P J P <ppandit@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* exec: do not call request_module() twice from search_binary_handler()Tetsuo Handa2011-10-161-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | commit 912193521b719fbfc2f16776febf5232fe8ba261 upstream. Currently, search_binary_handler() tries to load binary loader module using request_module() if a loader for the requested program is not yet loaded. But second attempt of request_module() does not affect the result of search_binary_handler(). If request_module() triggered recursion, calling request_module() twice causes 2 to the power of MAX_KMOD_CONCURRENT (= 50) repetitions. It is not an infinite loop but is sufficient for users to consider as a hang up. Therefore, this patch changes not to call request_module() twice, making 1 to the power of MAX_KMOD_CONCURRENT repetitions in case of recursion. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Richard Weinberger <richard@nod.at> Tested-by: Richard Weinberger <richard@nod.at> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Maxim Uvarov <muvarov@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* KEYS/DNS: Fix ____call_usermodehelper() to not lose the session keyringDavid Howells2011-06-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | ____call_usermodehelper() now erases any credentials set by the subprocess_inf::init() function. The problem is that commit 17f60a7da150 ("capabilites: allow the application of capability limits to usermode helpers") creates and commits new credentials with prepare_kernel_cred() after the call to the init() function. This wipes all keyrings after umh_keys_init() is called. The best way to deal with this is to put the init() call just prior to the commit_creds() call, and pass the cred pointer to init(). That means that umh_keys_init() and suchlike can modify the credentials _before_ they are published and potentially in use by the rest of the system. This prevents request_key() from working as it is prevented from passing the session keyring it set up with the authorisation token to /sbin/request-key, and so the latter can't assume the authority to instantiate the key. This causes the in-kernel DNS resolver to fail with ENOKEY unconditionally. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Eric Paris <eparis@redhat.com> Tested-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Revert "fs/exec.c: use BUILD_BUG_ON for VM_STACK_FLAGS & ↵Linus Torvalds2011-06-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | VM_STACK_INCOMPLETE_SETUP" This reverts commit 7f81c8890c15a10f5220bebae3b6dfae4961962a. It turns out that it's not actually a build-time check on x86-64 UML, which does some seriously crazy stuff with VM_STACK_FLAGS. The VM_STACK_FLAGS define depends on the arch-supplied VM_STACK_DEFAULT_FLAGS value, and on x86-64 UML we have arch/um/sys-x86_64/shared/sysdep/vm-flags.h: #define VM_STACK_DEFAULT_FLAGS \ (test_thread_flag(TIF_IA32) ? vm_stack_flags32 : vm_stack_flags) #define VM_STACK_DEFAULT_FLAGS vm_stack_flags (yes, seriously: two different #define's for that thing, with the first one being inside an "#ifdef TIF_IA32") It's possible that it is UML that should just be fixed in this area, but for now let's just undo the (very small) optimization. Reported-by: Randy Dunlap <randy.dunlap@oracle.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/exec.c: use BUILD_BUG_ON for VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUPMichal Hocko2011-06-151-1/+1
| | | | | | | | | | | | | Commit a8bef8ff6ea1 ("mm: migration: avoid race between shift_arg_pages() and rmap_walk() during migration by not migrating temporary stacks") introduced a BUG_ON() to ensure that VM_STACK_FLAGS and VM_STACK_INCOMPLETE_SETUP do not overlap. The check is a compile time one, so BUILD_BUG_ON is more appropriate. Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: delay address limit change until point of no returnMathias Krause2011-06-091-4/+1
| | | | | | | | | | | | | | | | | | | | | Unconditionally changing the address limit to USER_DS and not restoring it to its old value in the error path is wrong because it prevents us using kernel memory on repeated calls to this function. This, in fact, breaks the fallback of hard coded paths to the init program from being ever successful if the first candidate fails to load. With this patch applied switching to USER_DS is delayed until the point of no return is reached which makes it possible to have a multi-arch rootfs with one arch specific init binary for each of the (hard coded) probed paths. Since the address limit is already set to USER_DS when start_thread() will be invoked, this redundancy can be safely removed. Signed-off-by: Mathias Krause <minipli@googlemail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: add support for exe_file in core nameJiri Slaby2011-05-261-0/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now, exe_file is not proc FS dependent, so we can use it to name core file. So we add %E pattern for core file name cration which extract path from mm_struct->exe_file. Then it converts slashes to exclamation marks and pastes the result to the core file name itself. This is useful for environments where binary names are longer than 16 character (the current->comm limitation). Also where there are binaries with same name but in a different path. Further in case the binery itself changes its current->comm after exec. So by doing (s/$/#/ -- # is treated as git comment): $ sysctl kernel.core_pattern='core.%p.%e.%E' $ ln /bin/cat cat45678901234567890 $ ./cat45678901234567890 ^Z $ rm cat45678901234567890 $ fg ^\Quit (core dumped) $ ls core* we now get: core.2434.cat456789012345.!root!cat45678901234567890 (deleted) Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Reviewed-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: extract exe_file handling from procfsJiri Slaby2011-05-261-1/+0
| | | | | | | | | | | | | | | | | Setup and cleanup of mm_struct->exe_file is currently done in fs/proc/. This was because exe_file was needed only for /proc/<pid>/exe. Since we will need the exe_file functionality also for core dumps (so core name can contain full binary path), built this functionality always into the kernel. To achieve that move that out of proc FS to the kernel/ where in fact it should belong. By doing that we can make dup_mm_exe_file static. Also we can drop linux/proc_fs.h inclusion in fs/exec.c and kernel/fork.c. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: mmu_gather reworkPeter Zijlstra2011-05-251-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rework the existing mmu_gather infrastructure. The direct purpose of these patches was to allow preemptible mmu_gather, but even without that I think these patches provide an improvement to the status quo. The first 9 patches rework the mmu_gather infrastructure. For review purpose I've split them into generic and per-arch patches with the last of those a generic cleanup. The next patch provides generic RCU page-table freeing, and the followup is a patch converting s390 to use this. I've also got 4 patches from DaveM lined up (not included in this series) that uses this to implement gup_fast() for sparc64. Then there is one patch that extends the generic mmu_gather batching. After that follow the mm preemptibility patches, these make part of the mm a lot more preemptible. It converts i_mmap_lock and anon_vma->lock to mutexes which together with the mmu_gather rework makes mmu_gather preemptible as well. Making i_mmap_lock a mutex also enables a clean-up of the truncate code. This also allows for preemptible mmu_notifiers, something that XPMEM I think wants. Furthermore, it removes the new and universially detested unmap_mutex. This patch: Remove the first obstacle towards a fully preemptible mmu_gather. The current scheme assumes mmu_gather is always done with preemption disabled and uses per-cpu storage for the page batches. Change this to try and allocate a page for batching and in case of failure, use a small on-stack array to make some progress. Preemptible mmu_gather is desired in general and usable once i_mmap_lock becomes a mutex. Doing it before the mutex conversion saves us from having to rework the code by moving the mmu_gather bits inside the pte_lock. Also avoid flushing the tlb batches from under the pte lock, this is useful even without the i_mmap_lock conversion as it significantly reduces pte lock hold times. [akpm@linux-foundation.org: fix comment tpyo] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: David Miller <davem@davemloft.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Tony Luck <tony.luck@intel.com> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make expand_downwards() symmetrical with expand_upwards()Michal Hocko2011-05-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | Currently we have expand_upwards exported while expand_downwards is accessible only via expand_stack or expand_stack_downwards. check_stack_guard_page is a nice example of the asymmetry. It uses expand_stack for VM_GROWSDOWN while expand_upwards is called for VM_GROWSUP case. Let's clean this up by exporting both functions and make those names consistent. Let's use expand_{upwards,downwards} because expanding doesn't always involve stack manipulation (an example is ia64_do_page_fault which uses expand_upwards for registers backing store expansion). expand_downwards has to be defined for both CONFIG_STACK_GROWS{UP,DOWN} because get_arg_page calls the downwards version in the early process initialization phase for growsup configuration. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Hugh Dickins <hughd@google.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'tty-next' of ↵Linus Torvalds2011-05-231-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 * 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (48 commits) serial: 8250_pci: add support for Cronyx Omega PCI multiserial board. tty/serial: Fix break handling for PORT_TEGRA tty/serial: Add explicit PORT_TEGRA type n_tracerouter and n_tracesink ldisc additions. Intel PTI implementaiton of MIPI 1149.7. Kernel documentation for the PTI feature. export kernel call get_task_comm(). tty: Remove to support serial for S5P6442 pch_phub: Support new device ML7223 8250_pci: Add support for the Digi/IBM PCIe 2-port Adapter ASoC: Update cx20442 for TTY API change pch_uart: Support new device ML7223 IOH parport: Use request_muxed_region for IT87 probe and lock tty/serial: add support for Xilinx PS UART n_gsm: Use print_hex_dump_bytes drivers/tty/moxa.c: Put correct tty value TTY: tty_io, annotate locking functions TTY: serial_core, remove superfluous set_task_state TTY: serial_core, remove invalid test Char: moxa, fix locking in moxa_write ... Fix up trivial conflicts in drivers/bluetooth/hci_ldisc.c and drivers/tty/serial/Makefile. I did the hci_ldisc thing as an evil merge, cleaning things up.
| * export kernel call get_task_comm().J Freyensee2011-05-131-0/+1
| | | | | | | | | | | | | | | | | | | | | | This allows drivers who call this function to be compiled modularly. Otherwise, a driver who is interested in this type of functionality has to implement their own get_task_comm() call, causing code duplication in the Linux source tree. Signed-off-by: J Freyensee <james_p_freyensee@linux.intel.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* | Merge branch 'exec_rm_compat' of ↵Linus Torvalds2011-05-231-25/+100
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc * 'exec_rm_compat' of git://git.kernel.org/pub/scm/linux/kernel/git/oleg/misc: exec: document acct_arg_size() exec: unify do_execve/compat_do_execve code exec: introduce struct user_arg_ptr exec: introduce get_user_arg_ptr() helper
| * | exec: document acct_arg_size()Oleg Nesterov2011-04-091-1/+6
| | | | | | | | | | | | | | | | | | | | | Add the comment to explain acct_arg_size(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
| * | exec: unify do_execve/compat_do_execve codeOleg Nesterov2011-04-091-12/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add the appropriate members into struct user_arg_ptr and teach get_user_arg_ptr() to handle is_compat = T case correctly. This allows us to remove the compat_do_execve() code from fs/compat.c and reimplement compat_do_execve() as the trivial wrapper on top of do_execve_common(is_compat => true). In fact, this fixes another (minor) bug. "compat_uptr_t str" can overflow after "str += len" in compat_copy_strings() if a 64bit application execs via sys32_execve(). Unexport acct_arg_size() and get_arg_page(), fs/compat.c doesn't need them any longer. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
| * | exec: introduce struct user_arg_ptrOleg Nesterov2011-04-091-12/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | No functional changes, preparation. Introduce struct user_arg_ptr, change do_execve() paths to use it instead of "char __user * const __user *argv". This makes the argv/envp arguments opaque, we are ready to handle the compat case which needs argv pointing to compat_uptr_t. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
| * | exec: introduce get_user_arg_ptr() helperOleg Nesterov2011-04-091-11/+25
| |/ | | | | | | | | | | | | | | | | | | | | | | Introduce get_user_arg_ptr() helper, convert count() and copy_strings() to use it. No functional changes, preparation. This helper is trivial, it just reads the pointer from argv/envp user-space array. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
* | signal: Use GROUP_STOP_PENDING to stop once for a single group stopTejun Heo2011-03-231-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently task->signal->group_stop_count is used to decide whether to stop for group stop. However, if there is a task in the group which is taking a long time to stop, other tasks which are continued by ptrace would repeatedly stop for the same group stop until the group stop is complete. Conversely, if a ptraced task is in TASK_TRACED state, the debugger won't get notified of group stops which is inconsistent compared to the ptraced task in any other state. This patch introduces GROUP_STOP_PENDING which tracks whether a task is yet to stop for the group stop in progress. The flag is set when a group stop starts and cleared when the task stops the first time for the group stop, and consulted whenever whether the task should participate in a group stop needs to be determined. Note that now tasks in TASK_TRACED also participate in group stop. This results in the following behavior changes. * For a single group stop, a ptracer would see at most one stop reported. * A ptracee in TASK_TRACED now also participates in group stop and the tracer would get the notification. However, as a ptraced task could be in TASK_STOPPED state or any ptrace trap could consume group stop, the notification may still be missing. These will be addressed with further patches. * A ptracee may start a group stop while one is still in progress if the tracer let it continue with stop signal delivery. Group stop code handles this correctly. Oleg: * Spotted that a task might skip signal check even when its GROUP_STOP_PENDING is set. Fixed by updating recalc_sigpending_tsk() to check GROUP_STOP_PENDING instead of group_stop_count. * Pointed out that task->group_stop should be cleared whenever task->signal->group_stop_count is cleared. Fixed accordingly. * Pointed out the behavior inconsistency between TASK_TRACED and RUNNING and the last behavior change. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Roland McGrath <roland@redhat.com>
* Small typo fix...Holger Hans Peter Freyther2011-03-211-1/+1
| | | | | | | | | | | | | | | | | Hi, I was backporting the coredump over pipe feature and noticed this small typo, I wish I would have something bigger to contribute... >From 15d6080e0ed4267da103c706917a33b1015e8804 Mon Sep 17 00:00:00 2001 From: Holger Hans Peter Freyther <holger@moiji-mobile.com> Date: Thu, 24 Feb 2011 17:42:50 +0100 Subject: [PATCH] fs: Fix a small typo in the comment The function is called umh_pipe_setup not uhm_pipe_setup. Signed-off-by: Holger Hans Peter Freyther <holger@moiji-mobile.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* switch do_filp_open() to struct open_flagsAl Viro2011-03-141-6/+12
| | | | | | | | | take calculation of open_flags by open(2) arguments into new helper in fs/open.c, move filp_open() over there, have it and do_sys_open() use that helper, switch exec.c callers of do_filp_open() to explicit (and constant) struct open_flags. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: sparse: add __FMODE_EXECNamhyung Kim2011-02-021-2/+2
| | | | | | | | | | | | | | | FMODE_EXEC is a constant type of fmode_t but was used with normal integer constants. This results in following warnings from sparse. Fix it using new macro __FMODE_EXEC. fs/exec.c:116:58: warning: restricted fmode_t degrades to integer fs/exec.c:689:58: warning: restricted fmode_t degrades to integer fs/fcntl.c:777:9: warning: restricted fmode_t degrades to integer Signed-off-by: Namhyung Kim <namhyung@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* install_special_mapping skips security_file_mmap check.Tavis Ormandy2010-12-151-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The install_special_mapping routine (used, for example, to setup the vdso) skips the security check before insert_vm_struct, allowing a local attacker to bypass the mmap_min_addr security restriction by limiting the available pages for special mappings. bprm_mm_init() also skips the check, and although I don't think this can be used to bypass any restrictions, I don't see any reason not to have the security check. $ uname -m x86_64 $ cat /proc/sys/vm/mmap_min_addr 65536 $ cat install_special_mapping.s section .bss resb BSS_SIZE section .text global _start _start: mov eax, __NR_pause int 0x80 $ nasm -D__NR_pause=29 -DBSS_SIZE=0xfffed000 -f elf -o install_special_mapping.o install_special_mapping.s $ ld -m elf_i386 -Ttext=0x10000 -Tbss=0x11000 -o install_special_mapping install_special_mapping.o $ ./install_special_mapping & [1] 14303 $ cat /proc/14303/maps 0000f000-00010000 r-xp 00000000 00:00 0 [vdso] 00010000-00011000 r-xp 00001000 00:19 2453665 /home/taviso/install_special_mapping 00011000-ffffe000 rwxp 00000000 00:00 0 [stack] It's worth noting that Red Hat are shipping with mmap_min_addr set to 4096. Signed-off-by: Tavis Ormandy <taviso@google.com> Acked-by: Kees Cook <kees@ubuntu.com> Acked-by: Robert Swiecki <swiecki@google.com> [ Changed to not drop the error code - akpm ] Reviewed-by: James Morris <jmorris@namei.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: copy-and-paste the fixes into compat_do_execve() pathsOleg Nesterov2010-11-301-4/+4
| | | | | | | | | | | | | | | | | | | | | | | Note: this patch targets 2.6.37 and tries to be as simple as possible. That is why it adds more copy-and-paste horror into fs/compat.c and uglifies fs/exec.c, this will be cleanuped later. compat_copy_strings() plays with bprm->vma/mm directly and thus has two problems: it lacks the RLIMIT_STACK check and argv/envp memory is not visible to oom killer. Export acct_arg_size() and get_arg_page(), change compat_copy_strings() to use get_arg_page(), change compat_do_execve() to do acct_arg_size(0) as do_execve() does. Add the fatal_signal_pending/cond_resched checks into compat_count() and compat_copy_strings(), this matches the code in fs/exec.c and certainly makes sense. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: make argv/envp memory visible to oom-killerOleg Nesterov2010-11-301-2/+30
| | | | | | | | | | | | | | | | | | | | | | | | | Brad Spengler published a local memory-allocation DoS that evades the OOM-killer (though not the virtual memory RLIMIT): http://www.grsecurity.net/~spender/64bit_dos.c execve()->copy_strings() can allocate a lot of memory, but this is not visible to oom-killer, nobody can see the nascent bprm->mm and take it into account. With this patch get_arg_page() increments current's MM_ANONPAGES counter every time we allocate the new page for argv/envp. When do_execve() succeds or fails, we change this counter back. Technically this is not 100% correct, we can't know if the new page is swapped out and turn MM_ANONPAGES into MM_SWAPENTS, but I don't think this really matters and everything becomes correct once exec changes ->mm or fails. Reported-by: Brad Spengler <spender@grsecurity.net> Reviewed-and-discussed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: don't turn PF_KTHREAD off when a target command was not foundKOSAKI Motohiro2010-10-271-2/+1
| | | | | | | | | | | | | | | | | | Presently do_execve() turns PF_KTHREAD off before search_binary_handler(). THis has a theorical risk of PF_KTHREAD getting lost. We don't have to turn PF_KTHREAD off in the ENOEXEC case. This patch moves this flag modification to after the finding of the executable file. This is only a theorical issue because kthreads do not call do_execve() directly. But fixing would be better. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Roland McGrath <roland@redhat.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* core_pattern: fix truncation by core_pattern handler with long parametersXiaotian Feng2010-10-271-60/+95
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We met a parameter truncated issue, consider following: > echo "|/root/core_pattern_pipe_test %p /usr/libexec/blah-blah-blah \ %s %c %p %u %g 11 12345678901234567890123456789012345678 %t" > \ /proc/sys/kernel/core_pattern This is okay because the strings is less than CORENAME_MAX_SIZE. "cat /proc/sys/kernel/core_pattern" shows the whole string. but after we run core_pattern_pipe_test in man page, we found last parameter was truncated like below: argc[10]=<12807486> The root cause is core_pattern allows % specifiers, which need to be replaced during parse time, but the replace may expand the strings to larger than CORENAME_MAX_SIZE. So if the last parameter is % specifiers, the replace code is using snprintf(out_ptr, out_end - out_ptr, ...), this will write out of corename array. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Neil Horman <nhorman@tuxdriver.com> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* signals: move cred_guard_mutex from task_struct to signal_structKOSAKI Motohiro2010-10-271-5/+5
| | | | | | | | | | | | | | | | Oleg Nesterov pointed out we have to prevent multiple-threads-inside-exec itself and we can reuse ->cred_guard_mutex for it. Yes, concurrent execve() has no worth. Let's move ->cred_guard_mutex from task_struct to signal_struct. It naturally prevent multiple-threads-inside-exec. Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Roland McGrath <roland@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* oom: add per-mm oom disable countYing Han2010-10-261-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's pointless to kill a task if another thread sharing its mm cannot be killed to allow future memory freeing. A subsequent patch will prevent kills in such cases, but first it's necessary to have a way to flag a task that shares memory with an OOM_DISABLE task that doesn't incur an additional tasklist scan, which would make select_bad_process() an O(n^2) function. This patch adds an atomic counter to struct mm_struct that follows how many threads attached to it have an oom_score_adj of OOM_SCORE_ADJ_MIN. They cannot be killed by the kernel, so their memory cannot be freed in oom conditions. This only requires task_lock() on the task that we're operating on, it does not require mm->mmap_sem since task_lock() pins the mm and the operation is atomic. [rientjes@google.com: changelog and sys_unshare() code] [rientjes@google.com: protect oom_disable_count with task_lock in fork] [rientjes@google.com: use old_mm for oom_disable_count in exec] Signed-off-by: Ying Han <yinghan@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Export dump_{write,seek} to binary loader modulesLinus Torvalds2010-10-141-0/+2
| | | | | | | If you build aout support as a module, you'll want these exported. Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Un-inline the core-dump helper functionsLinus Torvalds2010-10-141-0/+38
| | | | | | | | | | | | | | | | | | Tony Luck reports that the addition of the access_ok() check in commit 0eead9ab41da ("Don't dump task struct in a.out core-dumps") broke the ia64 compile due to missing the necessary header file includes. Rather than add yet another include (<asm/unistd.h>) to make everything happy, just uninline the silly core dump helper functions and move the bodies to fs/exec.c where they make a lot more sense. dump_seek() in particular was too big to be an inline function anyway, and none of them are in any way performance-critical. And we really don't need to mess up our include file headers more than they already are. Reported-and-tested-by: Tony Luck <tony.luck@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* execve: make responsive to SIGKILL with large argumentsRoland McGrath2010-09-101-0/+7
| | | | | | | | | | | | | | | | | | | An execve with a very large total of argument/environment strings can take a really long time in the execve system call. It runs uninterruptibly to count and copy all the strings. This change makes it abort the exec quickly if sent a SIGKILL. Note that this is the conservative change, to interrupt only for SIGKILL, by using fatal_signal_pending(). It would be perfectly correct semantics to let any signal interrupt the string-copying in execve, i.e. use signal_pending() instead of fatal_signal_pending(). We'll save that change for later, since it could have user-visible consequences, such as having a timer set too quickly make it so that an execve can never complete, though it always happened to work before. Signed-off-by: Roland McGrath <roland@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* execve: improve interactivity with large argumentsRoland McGrath2010-09-101-0/+2
| | | | | | | | | | | | | | | | This adds a preemption point during the copying of the argument and environment strings for execve, in copy_strings(). There is already a preemption point in the count() loop, so this doesn't add any new points in the abstract sense. When the total argument+environment strings are very large, the time spent copying them can be much more than a normal user time slice. So this change improves the interactivity of the rest of the system when one process is doing an execve with very large arguments. Signed-off-by: Roland McGrath <roland@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* setup_arg_pages: diagnose excessive argument sizeRoland McGrath2010-09-101-0/+5
| | | | | | | | | | | | | | | | | | | The CONFIG_STACK_GROWSDOWN variant of setup_arg_pages() does not check the size of the argument/environment area on the stack. When it is unworkably large, shift_arg_pages() hits its BUG_ON. This is exploitable with a very large RLIMIT_STACK limit, to create a crash pretty easily. Check that the initial stack is not too large to make it possible to map in any executable. We're not checking that the actual executable (or intepreter, for binfmt_elf) will fit. So those mappings might clobber part of the initial stack mapping. But that is just userland lossage that userland made happen, not a kernel problem. Signed-off-by: Roland McGrath <roland@redhat.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2010-08-181-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: fs: brlock vfsmount_lock fs: scale files_lock lglock: introduce special lglock and brlock spin locks tty: fix fu_list abuse fs: cleanup files_lock locking fs: remove extra lookup in __lookup_hash fs: fs_struct rwlock to spinlock apparmor: use task path helpers fs: dentry allocation consolidation fs: fix do_lookup false negative mbcache: Limit the maximum number of cache entries hostfs ->follow_link() braino hostfs: dumb (and usually harmless) tpyo - strncpy instead of strlcpy remove SWRITE* I/O types kill BH_Ordered flag vfs: update ctime when changing the file's permission by setfacl cramfs: only unlock new inodes fix reiserfs_evict_inode end_writeback second call
| * fs: fs_struct rwlock to spinlockNick Piggin2010-08-181-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | fs: fs_struct rwlock to spinlock struct fs_struct.lock is an rwlock with the read-side used to protect root and pwd members while taking references to them. Taking a reference to a path typically requires just 2 atomic ops, so the critical section is very small. Parallel read-side operations would have cacheline contention on the lock, the dentry, and the vfsmount cachelines, so the rwlock is unlikely to ever give a real parallelism increase. Replace it with a spinlock to avoid one or two atomic operations in typical path lookup fastpath. Signed-off-by: Nick Piggin <npiggin@kernel.dk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Make do_execve() take a const filename pointerDavid Howells2010-08-171-10/+11
|/ | | | | | | | | | | | | | | | | | | | | | | | | | Make do_execve() take a const filename pointer so that kernel_execve() compiles correctly on ARM: arch/arm/kernel/sys_arm.c:88: warning: passing argument 1 of 'do_execve' discards qualifiers from pointer target type This also requires the argv and envp arguments to be consted twice, once for the pointer array and once for the strings the array points to. This is because do_execve() passes a pointer to the filename (now const) to copy_strings_kernel(). A simpler alternative would be to cast the filename pointer in do_execve() when it's passed to copy_strings_kernel(). do_execve() may not change any of the strings it is passed as part of the argv or envp lists as they are some of them in .rodata, so marking these strings as const should be fine. Further kernel_execve() and sys_execve() need to be changed to match. This has been test built on x86_64, frv, arm and mips. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Ralf Baechle <ralf@linux-mips.org> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of git://git.infradead.org/users/eparis/notifyLinus Torvalds2010-08-101-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * 'for-linus' of git://git.infradead.org/users/eparis/notify: (132 commits) fanotify: use both marks when possible fsnotify: pass both the vfsmount mark and inode mark fsnotify: walk the inode and vfsmount lists simultaneously fsnotify: rework ignored mark flushing fsnotify: remove global fsnotify groups lists fsnotify: remove group->mask fsnotify: remove the global masks fsnotify: cleanup should_send_event fanotify: use the mark in handler functions audit: use the mark in handler functions dnotify: use the mark in handler functions inotify: use the mark in handler functions fsnotify: send fsnotify_mark to groups in event handling functions fsnotify: Exchange list heads instead of moving elements fsnotify: srcu to protect read side of inode and vfsmount locks fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called fsnotify: use _rcu functions for mark list traversal fsnotify: place marks on object in order of group memory address vfs/fsnotify: fsnotify_close can delay the final work in fput fsnotify: store struct file not struct path ... Fix up trivial delete/modify conflict in fs/notify/inotify/inotify.c.
| * fsnotify: pass a file instead of an inode to open, read, and writeEric Paris2010-07-281-2/+2
| | | | | | | | | | | | | | | | | | | | fanotify, the upcoming notification system actually needs a struct path so it can do opens in the context of listeners, and it needs a file so it can get f_flags from the original process. Close was the only operation that already was passing a struct file to the notification hook. This patch passes a file for access, modify, and open as well as they are easily available to these hooks. Signed-off-by: Eric Paris <eparis@redhat.com>
* | Merge branch 'bkl/core' of ↵Linus Torvalds2010-08-071-7/+0
|\ \ | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing * 'bkl/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing: do_coredump: Do not take BKL init: Remove the BKL from startup code
| * | do_coredump: Do not take BKLArnd Bergmann2010-07-101-7/+0
| |/ | | | | | | | | | | | | | | | | | | | | | | | | core_pattern is not actually protected and hasn't been ever since we introduced procfs support for sysctl -- a _long_ time. Don't take it here either. Also nothing inside do_coredump appears to require bkl protection. Signed-off-by: Arnd Bergmann <arnd@arndb.de> [ remove smp_lock.h headers ] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* | perf: Add non-exec mmap() trackingEric B Munson2010-06-091-0/+1
|/ | | | | | | | | | | | | | | | | Add the capacility to track data mmap()s. This can be used together with PERF_SAMPLE_ADDR for data profiling. Signed-off-by: Anton Blanchard <anton@samba.org> [Updated code for stable perf ABI] Signed-off-by: Eric B Munson <ebmunson@us.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <1274193049-25997-1-git-send-email-ebmunson@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* exit: avoid sig->count in de_thread/__exit_signal synchronizationOleg Nesterov2010-05-271-6/+5
| | | | | | | | | | | | | | | | | de_thread() and __exit_signal() use signal_struct->count/notify_count for synchronization. We can simplify the code and use ->notify_count only. Instead of comparing these two counters, we can change de_thread() to set ->notify_count = nr_of_sub_threads, then change __exit_signal() to dec-and-test this counter and notify group_exit_task. Note that __exit_signal() checks "notify_count > 0" just for symmetry with exit_notify(), we could just check it is != 0. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Roland McGrath <roland@redhat.com> Cc: Veaceslav Falico <vfalico@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: shift down_write(mmap_sem) into coredump_wait()Oleg Nesterov2010-05-271-12/+7
| | | | | | | | | | | | | | | | | - move the cprm.mm_flags checks up, before we take mmap_sem - move down_write(mmap_sem) and ->core_state check from do_coredump() to coredump_wait() This simplifies the code and makes the locking symmetrical. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Roland McGrath <roland@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: factor out put_cred() callsOleg Nesterov2010-05-271-10/+6
| | | | | | | | | | | | | Given that do_coredump() calls put_cred() on exit path, it is a bit ugly to do put_cred() + "goto fail" twice, just add the new "fail_creds" label. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Roland McGrath <roland@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: cleanup "ispipe" codeOleg Nesterov2010-05-271-22/+17
| | | | | | | | | | | | | | | | | | | | | - kill "int dump_count", argv_split(argcp) accepts argcp == NULL. - move "int dump_count" under " if (ispipe)" branch, fail_dropcount can check ispipe. - move "char **helper_argv" as well, change the code to do argv_free() right after call_usermodehelper_fns(). - If call_usermodehelper_fns() fails goto close_fail label instead of closing the file by hand. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Roland McGrath <roland@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* coredump: factor out the not-ispipe file checksOleg Nesterov2010-05-271-32/+31
| | | | | | | | | | | | | | | | do_coredump() does a lot of file checks after it opens the file or calls usermode helper. But all of these checks are only needed in !ispipe case. Move this code into the "else" branch and kill the ugly repetitive ispipe checks. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Roland McGrath <roland@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: replace call_usermodehelper_pipe with use of umh init function and ↵Neil Horman2010-05-271-7/+56
| | | | | | | | | | | | | | | | | | | resolve limit The first patch in this series introduced an init function to the call_usermodehelper api so that processes could be customized by caller. This patch takes advantage of that fact, by customizing the helper in do_coredump to create the pipe and set its core limit to one (for our recusrsion check). This lets us clean up the previous uglyness in the usermodehelper internals and factor call_usermodehelper out entirely. While I'm at it, we can also modify the helper setup to look for a core limit value of 1 rather than zero for our recursion check Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: migration: avoid race between shift_arg_pages() and rmap_walk() during ↵Mel Gorman2010-05-251-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | migration by not migrating temporary stacks Page migration requires rmap to be able to find all ptes mapping a page at all times, otherwise the migration entry can be instantiated, but it is possible to leave one behind if the second rmap_walk fails to find the page. If this page is later faulted, migration_entry_to_page() will call BUG because the page is locked indicating the page was migrated by the migration PTE not cleaned up. For example kernel BUG at include/linux/swapops.h:105! invalid opcode: 0000 [#1] PREEMPT SMP ... Call Trace: [<ffffffff810e951a>] handle_mm_fault+0x3f8/0x76a [<ffffffff8130c7a2>] do_page_fault+0x44a/0x46e [<ffffffff813099b5>] page_fault+0x25/0x30 [<ffffffff8114de33>] load_elf_binary+0x152a/0x192b [<ffffffff8111329b>] search_binary_handler+0x173/0x313 [<ffffffff81114896>] do_execve+0x219/0x30a [<ffffffff8100a5c6>] sys_execve+0x43/0x5e [<ffffffff8100320a>] stub_execve+0x6a/0xc0 RIP [<ffffffff811094ff>] migration_entry_wait+0xc1/0x129 There is a race between shift_arg_pages and migration that triggers this bug. A temporary stack is setup during exec and later moved. If migration moves a page in the temporary stack and the VMA is then removed before migration completes, the migration PTE may not be found leading to a BUG when the stack is faulted. This patch causes pages within the temporary stack during exec to be skipped by migration. It does this by marking the VMA covering the temporary stack with an otherwise impossible combination of VMA flags. These flags are cleared when the temporary stack is moved to its final location. [kamezawa.hiroyu@jp.fujitsu.com: idea for having migration skip temporary stacks] Signed-off-by: Mel Gorman <mel@csn.ul.ie> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* revert "procfs: provide stack information for threads" and its fixup commitsRobin Holt2010-05-111-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Originally, commit d899bf7b ("procfs: provide stack information for threads") attempted to introduce a new feature for showing where the threadstack was located and how many pages are being utilized by the stack. Commit c44972f1 ("procfs: disable per-task stack usage on NOMMU") was applied to fix the NO_MMU case. Commit 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on 64-bit") was applied to fix a bug in ia32 executables being loaded. Commit 9ebd4eba7 ("procfs: fix /proc/<pid>/stat stack pointer for kernel threads") was applied to fix a bug which had kernel threads printing a userland stack address. Commit 1306d603f ('proc: partially revert "procfs: provide stack information for threads"') was then applied to revert the stack pages being used to solve a significant performance regression. This patch nearly undoes the effect of all these patches. The reason for reverting these is it provides an unusable value in field 28. For x86_64, a fork will result in the task->stack_start value being updated to the current user top of stack and not the stack start address. This unpredictability of the stack_start value makes it worthless. That includes the intended use of showing how much stack space a thread has. Other architectures will get different values. As an example, ia64 gets 0. The do_fork() and copy_process() functions appear to treat the stack_start and stack_size parameters as architecture specific. I only partially reverted c44972f1 ("procfs: disable per-task stack usage on NOMMU") . If I had completely reverted it, I would have had to change mm/Makefile only build pagewalk.o when CONFIG_PROC_PAGE_MONITOR is configured. Since I could not test the builds without significant effort, I decided to not change mm/Makefile. I only partially reverted 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on 64-bit") . I left the KSTK_ESP() change in place as that seemed worthwhile. Signed-off-by: Robin Holt <holt@sgi.com> Cc: Stefani Seibold <stefani@seibold.net> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michal Simek <monstr@monstr.eu> Cc: Ingo Molnar <mingo@elte.hu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
generated by cgit v1.1 at 2024-04-30 15:54:58 +0000