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| author | Arjan van de Ven <arjan@infradead.org> | 2009-09-26 20:51:50 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-10-02 19:51:56 +0200 |
| commit | 11879ba5d9ab8174af9b9cefbb2396a54dfbf8c1 (patch) | |
| tree | 6f33aa93436dbf959e6c9e10f8b113801eca59cb /arch | |
| parent | 0d18b2e34bd1ad8f5bd3f3a17b5e7df132e511a9 (diff) | |
| download | kernel_samsung_smdk4412-11879ba5d9ab8174af9b9cefbb2396a54dfbf8c1.zip kernel_samsung_smdk4412-11879ba5d9ab8174af9b9cefbb2396a54dfbf8c1.tar.gz kernel_samsung_smdk4412-11879ba5d9ab8174af9b9cefbb2396a54dfbf8c1.tar.bz2 | |
x86: Simplify bound checks in the MTRR code
The current bound checks for copy_from_user in the MTRR driver are
not as obvious as they could be, and gcc agrees with that.
This patch simplifies the boundary checks to the point that gcc can
now prove to itself that the copy_from_user() is never going past
its bounds.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20090926205150.30797709@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/mtrr/if.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/mtrr/if.c b/arch/x86/kernel/cpu/mtrr/if.c index f04e725..3c1b12d 100644 --- a/arch/x86/kernel/cpu/mtrr/if.c +++ b/arch/x86/kernel/cpu/mtrr/if.c @@ -96,17 +96,24 @@ mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos) unsigned long long base, size; char *ptr; char line[LINE_SIZE]; + int length; size_t linelen; if (!capable(CAP_SYS_ADMIN)) return -EPERM; - if (!len) - return -EINVAL; memset(line, 0, LINE_SIZE); - if (len > LINE_SIZE) - len = LINE_SIZE; - if (copy_from_user(line, buf, len - 1)) + + length = len; + length--; + + if (length > LINE_SIZE - 1) + length = LINE_SIZE - 1; + + if (length < 0) + return -EINVAL; + + if (copy_from_user(line, buf, length)) return -EFAULT; linelen = strlen(line); |