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Fix i686 memchr for large input sizes

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Similar to BZ#19387 and BZ#20971, both i686 memchr optimized assembly
implementations (memchr-sse2-bsf and memchr-sse2) do not handle the
size overflow correctly.

It is shown by the new tests added by commit 3daef2c8ee, where
both implementation fails with size as SIZE_MAX.

This patch uses a similar strategy used on 3daef2c8ee, where
saturared math is used for overflow case.

Checked on i686-linux-gnu.

	[BZ #21014]
	* sysdeps/i386/i686/multiarch/memchr-sse2-bsf.S (MEMCHR): Avoid overflow
	in pointer addition.
	* sysdeps/i386/i686/multiarch/memchr-sse2.S (MEMCHR): Likewise.
This commit is contained in:
Adhemerval Zanella 2017-01-02 12:20:21 -02:00
parent 62210e7eb1
commit 23d27709a4
3 changed files with 22 additions and 3 deletions
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7
ChangeLog
View File

@ -1,3 +1,10 @@
2017-01-02 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #21014]
* sysdeps/i386/i686/multiarch/memchr-sse2-bsf.S (MEMCHR): Avoid overflow
in pointer addition.
* sysdeps/i386/i686/multiarch/memchr-sse2.S (MEMCHR): Likewise.
2017-01-02 Torvald Riegel <triegel@redhat.com>
* sysdeps/sparc/nptl/bits/pthreadtypes.h (pthread_cond_t): Adapt to

10
sysdeps/i386/i686/multiarch/memchr-sse2-bsf.S
View File

@ -149,9 +149,15 @@ L(crosscache):
.p2align 4
L(unaligned_no_match):
# ifndef USE_AS_RAWMEMCHR
sub $16, %edx
/* Calculate the last acceptable address and check for possible
addition overflow by using satured math:
edx = ecx + edx
edx |= -(edx < ecx) */
add %ecx, %edx
jle L(return_null)
sbb %eax, %eax
or %eax, %edx
sub $16, %edx
jbe L(return_null)
add $16, %edi
# else
add $16, %edx

8
sysdeps/i386/i686/multiarch/memchr-sse2.S
View File

@ -118,8 +118,14 @@ L(crosscache):
# ifndef USE_AS_RAWMEMCHR
jnz L(match_case2_prolog1)
lea -16(%edx), %edx
/* Calculate the last acceptable address and check for possible
addition overflow by using satured math:
edx = ecx + edx
edx |= -(edx < ecx) */
add %ecx, %edx
jle L(return_null)
sbb %eax, %eax
or %eax, %edx
jbe L(return_null)
lea 16(%edi), %edi
# else
jnz L(match_case1_prolog1)