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Fixes for hardened usercopy:

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- avoid signed math problems on unexpected compilers
 - avoid false positives at very end of kernel text range checks
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 Comment: Kees Cook <kees@outflux.net>
 
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Merge tag 'usercopy-v4.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardened usercopy fixes from Kees Cook:
 - avoid signed math problems on unexpected compilers
 - avoid false positives at very end of kernel text range checks

* tag 'usercopy-v4.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  usercopy: fix overlap check for kernel text
  usercopy: avoid potentially undefined behavior in pointer math
This commit is contained in:
Linus Torvalds 2016-08-23 14:32:38 -04:00
commit 7a1dcf6ada
1 changed files with 2 additions and 2 deletions
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4
mm/usercopy.c
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@ -83,7 +83,7 @@ static bool overlaps(const void *ptr, unsigned long n, unsigned long low,
unsigned long check_high = check_low + n;
/* Does not overlap if entirely above or entirely below. */
if (check_low >= high || check_high < low)
if (check_low >= high || check_high <= low)
return false;
return true;
@ -124,7 +124,7 @@ static inline const char *check_kernel_text_object(const void *ptr,
static inline const char *check_bogus_address(const void *ptr, unsigned long n)
{
/* Reject if object wraps past end of memory. */
if (ptr + n < ptr)
if ((unsigned long)ptr + n < (unsigned long)ptr)
return "<wrapped address>";
/* Reject if NULL or ZERO-allocation. */