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| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-02-15 20:27:21 -0600 |
|---|---|---|
| committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-02-16 02:11:16 -0600 |
| commit | e108c02a5e23c8c88ce66d8705d4a24bb6b9a8bf (patch) | |
| tree | aa7b3178016dfb0f5a270d900385d889016be1ee /sysdeps/x86_64/multiarch | |
| parent | 0281c7a7ec8f3f46d8e6f5f3d7fca548946dbfce (diff) | |
| download | glibc-e108c02a5e23c8c88ce66d8705d4a24bb6b9a8bf.tar.gz glibc-e108c02a5e23c8c88ce66d8705d4a24bb6b9a8bf.tar.xz glibc-e108c02a5e23c8c88ce66d8705d4a24bb6b9a8bf.zip | |
x86: Fix bug in strncmp-evex and strncmp-avx2 [BZ #28895]
Logic can read before the start of `s1` / `s2` if both `s1` and `s2` are near the start of a page. To avoid having the result contimated by these comparisons the `strcmp` variants would mask off these comparisons. This was missing in the `strncmp` variants causing the bug. This commit adds the masking to `strncmp` so that out of range comparisons don't affect the result. test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass as well a full xcheck on x86_64 linux. Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'sysdeps/x86_64/multiarch')
| -rw-r--r-- | sysdeps/x86_64/multiarch/strcmp-avx2.S | 1 | ||||
| -rw-r--r-- | sysdeps/x86_64/multiarch/strcmp-evex.S | 1 |
2 files changed, 2 insertions, 0 deletions
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S index 99e5349be8..07a5a2c889 100644 --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S @@ -661,6 +661,7 @@ L(ret8): # ifdef USE_AS_STRNCMP .p2align 4,, 10 L(return_page_cross_end_check): + andl %r10d, %ecx tzcntl %ecx, %ecx leal -VEC_SIZE(%rax, %rcx), %ecx cmpl %ecx, %edx diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S index 6f42e3155a..56d8c118e4 100644 --- a/sysdeps/x86_64/multiarch/strcmp-evex.S +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S @@ -689,6 +689,7 @@ L(ret8): # ifdef USE_AS_STRNCMP .p2align 4,, 10 L(return_page_cross_end_check): + andl %r10d, %ecx tzcntl %ecx, %ecx leal -VEC_SIZE(%rax, %rcx, SIZE_OF_CHAR), %ecx # ifdef USE_AS_WCSCMP |