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| author | H.J. Lu <hjl.tools@gmail.com> | 2022-12-01 16:36:02 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2022-12-02 08:18:41 -0800 |
| commit | e5672763c44f16ddbc42809f5def7c6a962602bd (patch) | |
| tree | a34a3791fc27a9402cb0f78c611e8d5de568c316 | |
| parent | f566b028524149ddfebe7f9770a3befb13b81a13 (diff) | |
| download | glibc-e5672763c44f16ddbc42809f5def7c6a962602bd.zip glibc-e5672763c44f16ddbc42809f5def7c6a962602bd.tar.gz glibc-e5672763c44f16ddbc42809f5def7c6a962602bd.tar.bz2 | |
x86-64 strncpy: Properly handle the length parameter [BZ# 29839]
On x32, the size_t parameter may be passed in the lower 32 bits of a
64-bit register with the non-zero upper 32 bits. The string/memory
functions written in assembly can only use the lower 32 bits of a
64-bit register as length or must clear the upper 32 bits before using
the full 64-bit register for length.
This pach fixes strncpy for x32. Tested on x86-64 and x32. On x86-64,
libc.so is the same with and without the fix.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
| -rw-r--r-- | sysdeps/x86_64/multiarch/strncpy-avx2.S | 4 | ||||
| -rw-r--r-- | sysdeps/x86_64/multiarch/strncpy-evex.S | 4 |
2 files changed, 8 insertions, 0 deletions
diff --git a/sysdeps/x86_64/multiarch/strncpy-avx2.S b/sysdeps/x86_64/multiarch/strncpy-avx2.S index e9afd8f..3e6350c 100644 --- a/sysdeps/x86_64/multiarch/strncpy-avx2.S +++ b/sysdeps/x86_64/multiarch/strncpy-avx2.S @@ -52,6 +52,10 @@ .section SECTION(.text), "ax", @progbits ENTRY(STRNCPY) +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +# endif /* Filter zero length strings and very long strings. Zero length strings just return, very long strings are handled by just running rep stos{b|l} to zero set (which will almost diff --git a/sysdeps/x86_64/multiarch/strncpy-evex.S b/sysdeps/x86_64/multiarch/strncpy-evex.S index 49eaf4c..dec8ccc 100644 --- a/sysdeps/x86_64/multiarch/strncpy-evex.S +++ b/sysdeps/x86_64/multiarch/strncpy-evex.S @@ -80,6 +80,10 @@ .section SECTION(.text), "ax", @progbits ENTRY(STRNCPY) +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +# endif /* Filter zero length strings and very long strings. Zero length strings just return, very long strings are handled by just running rep stos{b|l} to zero set (which will almost |