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| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-01-09 16:02:21 -0600 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2022-01-27 07:28:12 -0800 |
| commit | be6fb78a1fc4dab9a6afb6a428bd0293676dfad5 (patch) | |
| tree | d95ec43d7e32174f8159974ea912b6697b521eef | |
| parent | 646ec4ebe52a969041a2dafb4f2d7eadac221556 (diff) | |
| download | glibc-be6fb78a1fc4dab9a6afb6a428bd0293676dfad5.tar.gz | |
x86: Fix __wcsncmp_avx2 in strcmp-avx2.S [BZ# 28755]
Fixes [BZ# 28755] for wcsncmp by redirecting length >= 2^56 to
__wcscmp_avx2. For x86_64 this covers the entire address range so any
length larger could not possibly be used to bound `s1` or `s2`.
test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass.
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
(cherry picked from commit ddf0992cf57a93200e0c782e2a94d0733a5a0b87)
| -rw-r--r-- | sysdeps/x86_64/multiarch/strcmp-avx2.S | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S index c9f246415f..360370cb7a 100644 --- a/sysdeps/x86_64/multiarch/strcmp-avx2.S +++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S @@ -83,6 +83,16 @@ ENTRY (STRCMP) je L(char0) jb L(zero) # ifdef USE_AS_WCSCMP +# ifndef __ILP32__ + movq %rdx, %rcx + /* Check if length could overflow when multiplied by + sizeof(wchar_t). Checking top 8 bits will cover all potential + overflow cases as well as redirect cases where its impossible to + length to bound a valid memory region. In these cases just use + 'wcscmp'. */ + shrq $56, %rcx + jnz __wcscmp_avx2 +# endif /* Convert units: from wide to byte char. */ shl $2, %RDX_LP # endif |