| Message ID | 20221202003602.358708-1-hjl.tools@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86-64 strncpy: Properly handle the length parameter [BZ# 29839] | expand |
On Thu, Dec 1, 2022 at 4:36 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > 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. > --- > sysdeps/x86_64/multiarch/strncpy-avx2.S | 4 ++++ > sysdeps/x86_64/multiarch/strncpy-evex.S | 4 ++++ > 2 files changed, 8 insertions(+) > > diff --git a/sysdeps/x86_64/multiarch/strncpy-avx2.S b/sysdeps/x86_64/multiarch/strncpy-avx2.S > index e9afd8fbed..3e6350ce4a 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 49eaf4cbd9..dec8cccc2b 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 > -- > 2.38.1 > LGTM. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
diff --git a/sysdeps/x86_64/multiarch/strncpy-avx2.S b/sysdeps/x86_64/multiarch/strncpy-avx2.S index e9afd8fbed..3e6350ce4a 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 49eaf4cbd9..dec8cccc2b 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