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| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-09-20 17:58:04 -0700 |
|---|---|---|
| committer | Sunil K Pandey <skpgkp2@gmail.com> | 2022-11-24 18:06:14 -0800 |
| commit | c9e58ae23402eb82877de90fd8a18519c086ed87 (patch) | |
| tree | 72bfc0e21aac7e79c399f1ca23051689a6adc4a4 /sysdeps/x86_64/multiarch/strlen-avx2.S | |
| parent | 2b05bbfd35f9a7645a74dbeef56bf1000c8ee0b5 (diff) | |
| download | glibc-c9e58ae23402eb82877de90fd8a18519c086ed87.tar.gz glibc-c9e58ae23402eb82877de90fd8a18519c086ed87.tar.xz glibc-c9e58ae23402eb82877de90fd8a18519c086ed87.zip | |
x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591]
Previous implementation was adjusting length (rsi) to match bytes (eax), but since there is no bound to length this can cause overflow. Fix is to just convert the byte-count (eax) to length by dividing by sizeof (wchar_t) before the comparison. Full check passes on x86-64 and build succeeds w/ and w/o multiarch. (cherry picked from commit b0969fa53a28b4ab2159806bf6c99a98999502ee)
Diffstat (limited to 'sysdeps/x86_64/multiarch/strlen-avx2.S')
| -rw-r--r-- | sysdeps/x86_64/multiarch/strlen-avx2.S | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S index 376889668d..2a314f07da 100644 --- a/sysdeps/x86_64/multiarch/strlen-avx2.S +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S @@ -542,14 +542,11 @@ L(return_vzeroupper): L(cross_page_less_vec): tzcntl %eax, %eax # ifdef USE_AS_WCSLEN - /* NB: Multiply length by 4 to get byte count. */ - sall $2, %esi + /* NB: Divide by 4 to convert from byte-count to length. */ + shrl $2, %eax # endif cmpq %rax, %rsi cmovb %esi, %eax -# ifdef USE_AS_WCSLEN - shrl $2, %eax -# endif VZEROUPPER_RETURN # endif |