| Message ID | 20220110213540.1258344-2-goldstein.w.n@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,1/7] x86: Fix __wcsncmp_avx2 in strcmp-avx2.S [BZ# 28755] | expand |
On Mon, Jan 10, 2022 at 1:36 PM Noah Goldstein via Libc-alpha <libc-alpha@sourceware.org> wrote: > > Fixes [BZ# 28755] for wcsncmp by redirecting length >= 2^56 to > __wcscmp_evex. 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> > --- > sysdeps/x86_64/multiarch/strcmp-evex.S | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S > index 1d971f3889..0cd939d5af 100644 > --- a/sysdeps/x86_64/multiarch/strcmp-evex.S > +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S > @@ -104,6 +104,16 @@ 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_evex > +# endif > /* Convert units: from wide to byte char. */ > shl $2, %RDX_LP > # endif > -- > 2.25.1 > LGTM. Reviewed-by: H.J. Lu <hjl.tools@gmail.com> Thanks.
On Mon, Jan 10, 2022 at 6:15 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Mon, Jan 10, 2022 at 1:36 PM Noah Goldstein via Libc-alpha > <libc-alpha@sourceware.org> wrote: > > > > Fixes [BZ# 28755] for wcsncmp by redirecting length >= 2^56 to > > __wcscmp_evex. 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> > > --- > > sysdeps/x86_64/multiarch/strcmp-evex.S | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S > > index 1d971f3889..0cd939d5af 100644 > > --- a/sysdeps/x86_64/multiarch/strcmp-evex.S > > +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S > > @@ -104,6 +104,16 @@ 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_evex > > +# endif > > /* Convert units: from wide to byte char. */ > > shl $2, %RDX_LP > > # endif > > -- > > 2.25.1 > > > > LGTM. > > Reviewed-by: H.J. Lu <hjl.tools@gmail.com> > > Thanks. > > -- > H.J. I am backporting this to 2.34 branch.
On Wed, Jan 26, 2022 at 2:06 PM H.J. Lu via Libc-alpha <libc-alpha@sourceware.org> wrote: > > On Mon, Jan 10, 2022 at 6:15 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > > > On Mon, Jan 10, 2022 at 1:36 PM Noah Goldstein via Libc-alpha > > <libc-alpha@sourceware.org> wrote: > > > > > > Fixes [BZ# 28755] for wcsncmp by redirecting length >= 2^56 to > > > __wcscmp_evex. 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> > > > --- > > > sysdeps/x86_64/multiarch/strcmp-evex.S | 10 ++++++++++ > > > 1 file changed, 10 insertions(+) > > > > > > diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S > > > index 1d971f3889..0cd939d5af 100644 > > > --- a/sysdeps/x86_64/multiarch/strcmp-evex.S > > > +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S > > > @@ -104,6 +104,16 @@ 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_evex > > > +# endif > > > /* Convert units: from wide to byte char. */ > > > shl $2, %RDX_LP > > > # endif > > > -- > > > 2.25.1 > > > > > > > LGTM. > > > > Reviewed-by: H.J. Lu <hjl.tools@gmail.com> > > > > Thanks. > > > > -- > > H.J. > > I am backporting this to 2.34 branch. > > -- > H.J. I would like to backport this patch to release branches. Any comments or objections? --Sunil
diff --git a/sysdeps/x86_64/multiarch/strcmp-evex.S b/sysdeps/x86_64/multiarch/strcmp-evex.S index 1d971f3889..0cd939d5af 100644 --- a/sysdeps/x86_64/multiarch/strcmp-evex.S +++ b/sysdeps/x86_64/multiarch/strcmp-evex.S @@ -104,6 +104,16 @@ 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_evex +# endif /* Convert units: from wide to byte char. */ shl $2, %RDX_LP # endif
Fixes [BZ# 28755] for wcsncmp by redirecting length >= 2^56 to __wcscmp_evex. 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> --- sysdeps/x86_64/multiarch/strcmp-evex.S | 10 ++++++++++ 1 file changed, 10 insertions(+)