From c18508394610b47964ef6c2d4d71b85873ce10fe Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Mon, 25 Feb 2013 10:20:36 -0500 Subject: Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys commit 8aec0f5d4137532de14e6554fd5dd201ff3a3c49 upstream. Looking at mm/process_vm_access.c:process_vm_rw() and comparing it to compat_process_vm_rw() shows that the compatibility code requires an explicit "access_ok()" check before calling compat_rw_copy_check_uvector(). The same difference seems to appear when we compare fs/read_write.c:do_readv_writev() to fs/compat.c:compat_do_readv_writev(). This subtle difference between the compat and non-compat requirements should probably be debated, as it seems to be error-prone. In fact, there are two others sites that use this function in the Linux kernel, and they both seem to get it wrong: Now shifting our attention to fs/aio.c, we see that aio_setup_iocb() also ends up calling compat_rw_copy_check_uvector() through aio_setup_vectored_rw(). Unfortunately, the access_ok() check appears to be missing. Same situation for security/keys/compat.c:compat_keyctl_instantiate_key_iov(). I propose that we add the access_ok() check directly into compat_rw_copy_check_uvector(), so callers don't have to worry about it, and it therefore makes the compat call code similar to its non-compat counterpart. Place the access_ok() check in the same location where copy_from_user() can trigger a -EFAULT error in the non-compat code, so the ABI behaviors are alike on both compat and non-compat. While we are here, fix compat_do_readv_writev() so it checks for compat_rw_copy_check_uvector() negative return values. And also, fix a memory leak in compat_keyctl_instantiate_key_iov() error handling. Acked-by: Linus Torvalds Acked-by: Al Viro Signed-off-by: Mathieu Desnoyers Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- security/keys/compat.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'security') diff --git a/security/keys/compat.c b/security/keys/compat.c index 338b510..10a6e4c 100644 --- a/security/keys/compat.c +++ b/security/keys/compat.c @@ -40,12 +40,12 @@ long compat_keyctl_instantiate_key_iov( ARRAY_SIZE(iovstack), iovstack, &iov); if (ret < 0) - return ret; + goto err; if (ret == 0) goto no_payload_free; ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid); - +err: if (iov != iovstack) kfree(iov); return ret; -- cgit v1.1