diff mbox series

[v1] x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591]

Message ID 20220921005804.7131-1-goldstein.w.n@gmail.com
State New
Headers show
Series [v1] x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591] | expand

Commit Message

Noah Goldstein Sept. 21, 2022, 12:58 a.m. UTC 
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.
---
 string/test-strnlen.c                  | 70 +++++++++++++++-----------
 sysdeps/x86_64/multiarch/strlen-avx2.S |  7 +--
 2 files changed, 43 insertions(+), 34 deletions(-)

Comments

H.J. Lu Sept. 21, 2022, 10:01 p.m. UTC | #1 
On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> 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.
> ---
>  string/test-strnlen.c                  | 70 +++++++++++++++-----------
>  sysdeps/x86_64/multiarch/strlen-avx2.S |  7 +--
>  2 files changed, 43 insertions(+), 34 deletions(-)
>
> diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> index 4a9375112a..5cbaf4b734 100644
> --- a/string/test-strnlen.c
> +++ b/string/test-strnlen.c
> @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
>  {
>    size_t i;
>
> -  align &= 63;
> +  align &= (getpagesize () / sizeof (CHAR) - 1);
>    if ((align + len) * sizeof (CHAR) >= page_size)
>      return;
>
> @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
>  static void
>  do_overflow_tests (void)
>  {
> -  size_t i, j, len;
> +  size_t i, j, al_idx, repeats, len;
>    const size_t one = 1;
>    uintptr_t buf_addr = (uintptr_t) buf1;
> +  const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
>
> -  for (i = 0; i < 750; ++i)
> +  for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
> +       al_idx++)
>      {
> -      do_test (1, i, SIZE_MAX, BIG_CHAR);
> -
> -      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
> -      do_test (0, i, i - buf_addr, BIG_CHAR);
> -      do_test (0, i, -buf_addr - i, BIG_CHAR);
> -      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> -      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> -
> -      len = 0;
> -      for (j = 8 * sizeof(size_t) - 1; j ; --j)
> -        {
> -          len |= one << j;
> -          do_test (0, i, len - i, BIG_CHAR);
> -          do_test (0, i, len + i, BIG_CHAR);
> -          do_test (0, i, len - buf_addr - i, BIG_CHAR);
> -          do_test (0, i, len - buf_addr + i, BIG_CHAR);
> -
> -          do_test (0, i, ~len - i, BIG_CHAR);
> -          do_test (0, i, ~len + i, BIG_CHAR);
> -          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
> -          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
> -
> -          do_test (0, i, -buf_addr, BIG_CHAR);
> -          do_test (0, i, j - buf_addr, BIG_CHAR);
> -          do_test (0, i, -buf_addr - j, BIG_CHAR);
> -        }
> +      for (repeats = 0; repeats < 2; ++repeats)
> +       {
> +         size_t align = repeats ? (getpagesize () - alignments[al_idx])
> +                                : alignments[al_idx];
> +         align /= sizeof (CHAR);
> +         for (i = 0; i < 750; ++i)
> +           {
> +             do_test (align, i, SIZE_MAX, BIG_CHAR);
> +
> +             do_test (align, i, SIZE_MAX - i, BIG_CHAR);
> +             do_test (align, i, i - buf_addr, BIG_CHAR);
> +             do_test (align, i, -buf_addr - i, BIG_CHAR);
> +             do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> +             do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> +
> +             len = 0;
> +             for (j = 8 * sizeof (size_t) - 1; j; --j)
> +               {
> +                 len |= one << j;
> +                 do_test (align, i, len, BIG_CHAR);
> +                 do_test (align, i, len - i, BIG_CHAR);
> +                 do_test (align, i, len + i, BIG_CHAR);
> +                 do_test (align, i, len - buf_addr - i, BIG_CHAR);
> +                 do_test (align, i, len - buf_addr + i, BIG_CHAR);
> +
> +                 do_test (align, i, ~len - i, BIG_CHAR);
> +                 do_test (align, i, ~len + i, BIG_CHAR);
> +                 do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
> +                 do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
> +
> +                 do_test (align, i, -buf_addr, BIG_CHAR);
> +                 do_test (align, i, j - buf_addr, BIG_CHAR);
> +                 do_test (align, i, -buf_addr - j, BIG_CHAR);
> +               }
> +           }
> +       }
>      }
>  }
>
> diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
> index 0593fb303b..b9b58ef599 100644
> --- a/sysdeps/x86_64/multiarch/strlen-avx2.S
> +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
> @@ -544,14 +544,11 @@ 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
>
> --
> 2.34.1
>

LGTM.

Thanks.
Sunil Pandey Nov. 23, 2022, 10:20 p.m. UTC | #2 
On Wed, Sep 21, 2022 at 3:02 PM H.J. Lu via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > 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.
> > ---
> >  string/test-strnlen.c                  | 70 +++++++++++++++-----------
> >  sysdeps/x86_64/multiarch/strlen-avx2.S |  7 +--
> >  2 files changed, 43 insertions(+), 34 deletions(-)
> >
> > diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> > index 4a9375112a..5cbaf4b734 100644
> > --- a/string/test-strnlen.c
> > +++ b/string/test-strnlen.c
> > @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> >  {
> >    size_t i;
> >
> > -  align &= 63;
> > +  align &= (getpagesize () / sizeof (CHAR) - 1);
> >    if ((align + len) * sizeof (CHAR) >= page_size)
> >      return;
> >
> > @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> >  static void
> >  do_overflow_tests (void)
> >  {
> > -  size_t i, j, len;
> > +  size_t i, j, al_idx, repeats, len;
> >    const size_t one = 1;
> >    uintptr_t buf_addr = (uintptr_t) buf1;
> > +  const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
> >
> > -  for (i = 0; i < 750; ++i)
> > +  for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
> > +       al_idx++)
> >      {
> > -      do_test (1, i, SIZE_MAX, BIG_CHAR);
> > -
> > -      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
> > -      do_test (0, i, i - buf_addr, BIG_CHAR);
> > -      do_test (0, i, -buf_addr - i, BIG_CHAR);
> > -      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > -      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > -
> > -      len = 0;
> > -      for (j = 8 * sizeof(size_t) - 1; j ; --j)
> > -        {
> > -          len |= one << j;
> > -          do_test (0, i, len - i, BIG_CHAR);
> > -          do_test (0, i, len + i, BIG_CHAR);
> > -          do_test (0, i, len - buf_addr - i, BIG_CHAR);
> > -          do_test (0, i, len - buf_addr + i, BIG_CHAR);
> > -
> > -          do_test (0, i, ~len - i, BIG_CHAR);
> > -          do_test (0, i, ~len + i, BIG_CHAR);
> > -          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
> > -          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
> > -
> > -          do_test (0, i, -buf_addr, BIG_CHAR);
> > -          do_test (0, i, j - buf_addr, BIG_CHAR);
> > -          do_test (0, i, -buf_addr - j, BIG_CHAR);
> > -        }
> > +      for (repeats = 0; repeats < 2; ++repeats)
> > +       {
> > +         size_t align = repeats ? (getpagesize () - alignments[al_idx])
> > +                                : alignments[al_idx];
> > +         align /= sizeof (CHAR);
> > +         for (i = 0; i < 750; ++i)
> > +           {
> > +             do_test (align, i, SIZE_MAX, BIG_CHAR);
> > +
> > +             do_test (align, i, SIZE_MAX - i, BIG_CHAR);
> > +             do_test (align, i, i - buf_addr, BIG_CHAR);
> > +             do_test (align, i, -buf_addr - i, BIG_CHAR);
> > +             do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > +             do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > +
> > +             len = 0;
> > +             for (j = 8 * sizeof (size_t) - 1; j; --j)
> > +               {
> > +                 len |= one << j;
> > +                 do_test (align, i, len, BIG_CHAR);
> > +                 do_test (align, i, len - i, BIG_CHAR);
> > +                 do_test (align, i, len + i, BIG_CHAR);
> > +                 do_test (align, i, len - buf_addr - i, BIG_CHAR);
> > +                 do_test (align, i, len - buf_addr + i, BIG_CHAR);
> > +
> > +                 do_test (align, i, ~len - i, BIG_CHAR);
> > +                 do_test (align, i, ~len + i, BIG_CHAR);
> > +                 do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
> > +                 do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
> > +
> > +                 do_test (align, i, -buf_addr, BIG_CHAR);
> > +                 do_test (align, i, j - buf_addr, BIG_CHAR);
> > +                 do_test (align, i, -buf_addr - j, BIG_CHAR);
> > +               }
> > +           }
> > +       }
> >      }
> >  }
> >
> > diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > index 0593fb303b..b9b58ef599 100644
> > --- a/sysdeps/x86_64/multiarch/strlen-avx2.S
> > +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > @@ -544,14 +544,11 @@ 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
> >
> > --
> > 2.34.1
> >
>
> LGTM.
>
> Thanks.
>
> --
> H.J.

I would like to backport this patch to affected release branches  from
2.36 to 2.33.

Any comments/suggestions or objections on this.

--Sunil
H.J. Lu Nov. 24, 2022, 12:22 a.m. UTC | #3 
On Wed, Nov 23, 2022 at 2:21 PM Sunil Pandey <skpgkp2@gmail.com> wrote:
>
> On Wed, Sep 21, 2022 at 3:02 PM H.J. Lu via Libc-alpha
> <libc-alpha@sourceware.org> wrote:
> >
> > On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > >
> > > 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.
> > > ---
> > >  string/test-strnlen.c                  | 70 +++++++++++++++-----------
> > >  sysdeps/x86_64/multiarch/strlen-avx2.S |  7 +--
> > >  2 files changed, 43 insertions(+), 34 deletions(-)
> > >
> > > diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> > > index 4a9375112a..5cbaf4b734 100644
> > > --- a/string/test-strnlen.c
> > > +++ b/string/test-strnlen.c
> > > @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> > >  {
> > >    size_t i;
> > >
> > > -  align &= 63;
> > > +  align &= (getpagesize () / sizeof (CHAR) - 1);
> > >    if ((align + len) * sizeof (CHAR) >= page_size)
> > >      return;
> > >
> > > @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> > >  static void
> > >  do_overflow_tests (void)
> > >  {
> > > -  size_t i, j, len;
> > > +  size_t i, j, al_idx, repeats, len;
> > >    const size_t one = 1;
> > >    uintptr_t buf_addr = (uintptr_t) buf1;
> > > +  const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
> > >
> > > -  for (i = 0; i < 750; ++i)
> > > +  for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
> > > +       al_idx++)
> > >      {
> > > -      do_test (1, i, SIZE_MAX, BIG_CHAR);
> > > -
> > > -      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
> > > -      do_test (0, i, i - buf_addr, BIG_CHAR);
> > > -      do_test (0, i, -buf_addr - i, BIG_CHAR);
> > > -      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > > -      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > > -
> > > -      len = 0;
> > > -      for (j = 8 * sizeof(size_t) - 1; j ; --j)
> > > -        {
> > > -          len |= one << j;
> > > -          do_test (0, i, len - i, BIG_CHAR);
> > > -          do_test (0, i, len + i, BIG_CHAR);
> > > -          do_test (0, i, len - buf_addr - i, BIG_CHAR);
> > > -          do_test (0, i, len - buf_addr + i, BIG_CHAR);
> > > -
> > > -          do_test (0, i, ~len - i, BIG_CHAR);
> > > -          do_test (0, i, ~len + i, BIG_CHAR);
> > > -          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
> > > -          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
> > > -
> > > -          do_test (0, i, -buf_addr, BIG_CHAR);
> > > -          do_test (0, i, j - buf_addr, BIG_CHAR);
> > > -          do_test (0, i, -buf_addr - j, BIG_CHAR);
> > > -        }
> > > +      for (repeats = 0; repeats < 2; ++repeats)
> > > +       {
> > > +         size_t align = repeats ? (getpagesize () - alignments[al_idx])
> > > +                                : alignments[al_idx];
> > > +         align /= sizeof (CHAR);
> > > +         for (i = 0; i < 750; ++i)
> > > +           {
> > > +             do_test (align, i, SIZE_MAX, BIG_CHAR);
> > > +
> > > +             do_test (align, i, SIZE_MAX - i, BIG_CHAR);
> > > +             do_test (align, i, i - buf_addr, BIG_CHAR);
> > > +             do_test (align, i, -buf_addr - i, BIG_CHAR);
> > > +             do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > > +             do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > > +
> > > +             len = 0;
> > > +             for (j = 8 * sizeof (size_t) - 1; j; --j)
> > > +               {
> > > +                 len |= one << j;
> > > +                 do_test (align, i, len, BIG_CHAR);
> > > +                 do_test (align, i, len - i, BIG_CHAR);
> > > +                 do_test (align, i, len + i, BIG_CHAR);
> > > +                 do_test (align, i, len - buf_addr - i, BIG_CHAR);
> > > +                 do_test (align, i, len - buf_addr + i, BIG_CHAR);
> > > +
> > > +                 do_test (align, i, ~len - i, BIG_CHAR);
> > > +                 do_test (align, i, ~len + i, BIG_CHAR);
> > > +                 do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
> > > +                 do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
> > > +
> > > +                 do_test (align, i, -buf_addr, BIG_CHAR);
> > > +                 do_test (align, i, j - buf_addr, BIG_CHAR);
> > > +                 do_test (align, i, -buf_addr - j, BIG_CHAR);
> > > +               }
> > > +           }
> > > +       }
> > >      }
> > >  }
> > >
> > > diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > index 0593fb303b..b9b58ef599 100644
> > > --- a/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > @@ -544,14 +544,11 @@ 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
> > >
> > > --
> > > 2.34.1
> > >
> >
> > LGTM.
> >
> > Thanks.
> >
> > --
> > H.J.
>
> I would like to backport this patch to affected release branches  from
> 2.36 to 2.33.
>
> Any comments/suggestions or objections on this.
>

OK.

Thanks.
Sunil Pandey Nov. 24, 2022, 3:04 a.m. UTC | #4 
On Wed, Nov 23, 2022 at 4:23 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Wed, Nov 23, 2022 at 2:21 PM Sunil Pandey <skpgkp2@gmail.com> wrote:
> >
> > On Wed, Sep 21, 2022 at 3:02 PM H.J. Lu via Libc-alpha
> > <libc-alpha@sourceware.org> wrote:
> > >
> > > On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > >
> > > > 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.
> > > > ---
> > > >  string/test-strnlen.c                  | 70 +++++++++++++++-----------
> > > >  sysdeps/x86_64/multiarch/strlen-avx2.S |  7 +--
> > > >  2 files changed, 43 insertions(+), 34 deletions(-)
> > > >
> > > > diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> > > > index 4a9375112a..5cbaf4b734 100644
> > > > --- a/string/test-strnlen.c
> > > > +++ b/string/test-strnlen.c
> > > > @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> > > >  {
> > > >    size_t i;
> > > >
> > > > -  align &= 63;
> > > > +  align &= (getpagesize () / sizeof (CHAR) - 1);
> > > >    if ((align + len) * sizeof (CHAR) >= page_size)
> > > >      return;
> > > >
> > > > @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> > > >  static void
> > > >  do_overflow_tests (void)
> > > >  {
> > > > -  size_t i, j, len;
> > > > +  size_t i, j, al_idx, repeats, len;
> > > >    const size_t one = 1;
> > > >    uintptr_t buf_addr = (uintptr_t) buf1;
> > > > +  const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
> > > >
> > > > -  for (i = 0; i < 750; ++i)
> > > > +  for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
> > > > +       al_idx++)
> > > >      {
> > > > -      do_test (1, i, SIZE_MAX, BIG_CHAR);
> > > > -
> > > > -      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
> > > > -      do_test (0, i, i - buf_addr, BIG_CHAR);
> > > > -      do_test (0, i, -buf_addr - i, BIG_CHAR);
> > > > -      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > > > -      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > > > -
> > > > -      len = 0;
> > > > -      for (j = 8 * sizeof(size_t) - 1; j ; --j)
> > > > -        {
> > > > -          len |= one << j;
> > > > -          do_test (0, i, len - i, BIG_CHAR);
> > > > -          do_test (0, i, len + i, BIG_CHAR);
> > > > -          do_test (0, i, len - buf_addr - i, BIG_CHAR);
> > > > -          do_test (0, i, len - buf_addr + i, BIG_CHAR);
> > > > -
> > > > -          do_test (0, i, ~len - i, BIG_CHAR);
> > > > -          do_test (0, i, ~len + i, BIG_CHAR);
> > > > -          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
> > > > -          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
> > > > -
> > > > -          do_test (0, i, -buf_addr, BIG_CHAR);
> > > > -          do_test (0, i, j - buf_addr, BIG_CHAR);
> > > > -          do_test (0, i, -buf_addr - j, BIG_CHAR);
> > > > -        }
> > > > +      for (repeats = 0; repeats < 2; ++repeats)
> > > > +       {
> > > > +         size_t align = repeats ? (getpagesize () - alignments[al_idx])
> > > > +                                : alignments[al_idx];
> > > > +         align /= sizeof (CHAR);
> > > > +         for (i = 0; i < 750; ++i)
> > > > +           {
> > > > +             do_test (align, i, SIZE_MAX, BIG_CHAR);
> > > > +
> > > > +             do_test (align, i, SIZE_MAX - i, BIG_CHAR);
> > > > +             do_test (align, i, i - buf_addr, BIG_CHAR);
> > > > +             do_test (align, i, -buf_addr - i, BIG_CHAR);
> > > > +             do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > > > +             do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > > > +
> > > > +             len = 0;
> > > > +             for (j = 8 * sizeof (size_t) - 1; j; --j)
> > > > +               {
> > > > +                 len |= one << j;
> > > > +                 do_test (align, i, len, BIG_CHAR);
> > > > +                 do_test (align, i, len - i, BIG_CHAR);
> > > > +                 do_test (align, i, len + i, BIG_CHAR);
> > > > +                 do_test (align, i, len - buf_addr - i, BIG_CHAR);
> > > > +                 do_test (align, i, len - buf_addr + i, BIG_CHAR);
> > > > +
> > > > +                 do_test (align, i, ~len - i, BIG_CHAR);
> > > > +                 do_test (align, i, ~len + i, BIG_CHAR);
> > > > +                 do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
> > > > +                 do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
> > > > +
> > > > +                 do_test (align, i, -buf_addr, BIG_CHAR);
> > > > +                 do_test (align, i, j - buf_addr, BIG_CHAR);
> > > > +                 do_test (align, i, -buf_addr - j, BIG_CHAR);
> > > > +               }
> > > > +           }
> > > > +       }
> > > >      }
> > > >  }
> > > >
> > > > diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > > index 0593fb303b..b9b58ef599 100644
> > > > --- a/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > > +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > > @@ -544,14 +544,11 @@ 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
> > > >
> > > > --
> > > > 2.34.1
> > > >
> > >
> > > LGTM.
> > >
> > > Thanks.
> > >
> > > --
> > > H.J.
> >
> > I would like to backport this patch to affected release branches  from
> > 2.36 to 2.33.
> >
> > Any comments/suggestions or objections on this.
> >
>
> OK.
>
> Thanks.
>
>
> --
> H.J.

Just ran testing from 2.32 to 2.26. All of them have this issue.

Ok for 2.32 to 2.26 branches?

--Sunil
H.J. Lu Nov. 24, 2022, 3:12 a.m. UTC | #5 
On Wed, Nov 23, 2022 at 7:04 PM Sunil Pandey <skpgkp2@gmail.com> wrote:
>
> On Wed, Nov 23, 2022 at 4:23 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Wed, Nov 23, 2022 at 2:21 PM Sunil Pandey <skpgkp2@gmail.com> wrote:
> > >
> > > On Wed, Sep 21, 2022 at 3:02 PM H.J. Lu via Libc-alpha
> > > <libc-alpha@sourceware.org> wrote:
> > > >
> > > > On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> > > > >
> > > > > 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.
> > > > > ---
> > > > >  string/test-strnlen.c                  | 70 +++++++++++++++-----------
> > > > >  sysdeps/x86_64/multiarch/strlen-avx2.S |  7 +--
> > > > >  2 files changed, 43 insertions(+), 34 deletions(-)
> > > > >
> > > > > diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> > > > > index 4a9375112a..5cbaf4b734 100644
> > > > > --- a/string/test-strnlen.c
> > > > > +++ b/string/test-strnlen.c
> > > > > @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> > > > >  {
> > > > >    size_t i;
> > > > >
> > > > > -  align &= 63;
> > > > > +  align &= (getpagesize () / sizeof (CHAR) - 1);
> > > > >    if ((align + len) * sizeof (CHAR) >= page_size)
> > > > >      return;
> > > > >
> > > > > @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char)
> > > > >  static void
> > > > >  do_overflow_tests (void)
> > > > >  {
> > > > > -  size_t i, j, len;
> > > > > +  size_t i, j, al_idx, repeats, len;
> > > > >    const size_t one = 1;
> > > > >    uintptr_t buf_addr = (uintptr_t) buf1;
> > > > > +  const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
> > > > >
> > > > > -  for (i = 0; i < 750; ++i)
> > > > > +  for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
> > > > > +       al_idx++)
> > > > >      {
> > > > > -      do_test (1, i, SIZE_MAX, BIG_CHAR);
> > > > > -
> > > > > -      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
> > > > > -      do_test (0, i, i - buf_addr, BIG_CHAR);
> > > > > -      do_test (0, i, -buf_addr - i, BIG_CHAR);
> > > > > -      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > > > > -      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > > > > -
> > > > > -      len = 0;
> > > > > -      for (j = 8 * sizeof(size_t) - 1; j ; --j)
> > > > > -        {
> > > > > -          len |= one << j;
> > > > > -          do_test (0, i, len - i, BIG_CHAR);
> > > > > -          do_test (0, i, len + i, BIG_CHAR);
> > > > > -          do_test (0, i, len - buf_addr - i, BIG_CHAR);
> > > > > -          do_test (0, i, len - buf_addr + i, BIG_CHAR);
> > > > > -
> > > > > -          do_test (0, i, ~len - i, BIG_CHAR);
> > > > > -          do_test (0, i, ~len + i, BIG_CHAR);
> > > > > -          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
> > > > > -          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
> > > > > -
> > > > > -          do_test (0, i, -buf_addr, BIG_CHAR);
> > > > > -          do_test (0, i, j - buf_addr, BIG_CHAR);
> > > > > -          do_test (0, i, -buf_addr - j, BIG_CHAR);
> > > > > -        }
> > > > > +      for (repeats = 0; repeats < 2; ++repeats)
> > > > > +       {
> > > > > +         size_t align = repeats ? (getpagesize () - alignments[al_idx])
> > > > > +                                : alignments[al_idx];
> > > > > +         align /= sizeof (CHAR);
> > > > > +         for (i = 0; i < 750; ++i)
> > > > > +           {
> > > > > +             do_test (align, i, SIZE_MAX, BIG_CHAR);
> > > > > +
> > > > > +             do_test (align, i, SIZE_MAX - i, BIG_CHAR);
> > > > > +             do_test (align, i, i - buf_addr, BIG_CHAR);
> > > > > +             do_test (align, i, -buf_addr - i, BIG_CHAR);
> > > > > +             do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
> > > > > +             do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
> > > > > +
> > > > > +             len = 0;
> > > > > +             for (j = 8 * sizeof (size_t) - 1; j; --j)
> > > > > +               {
> > > > > +                 len |= one << j;
> > > > > +                 do_test (align, i, len, BIG_CHAR);
> > > > > +                 do_test (align, i, len - i, BIG_CHAR);
> > > > > +                 do_test (align, i, len + i, BIG_CHAR);
> > > > > +                 do_test (align, i, len - buf_addr - i, BIG_CHAR);
> > > > > +                 do_test (align, i, len - buf_addr + i, BIG_CHAR);
> > > > > +
> > > > > +                 do_test (align, i, ~len - i, BIG_CHAR);
> > > > > +                 do_test (align, i, ~len + i, BIG_CHAR);
> > > > > +                 do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
> > > > > +                 do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
> > > > > +
> > > > > +                 do_test (align, i, -buf_addr, BIG_CHAR);
> > > > > +                 do_test (align, i, j - buf_addr, BIG_CHAR);
> > > > > +                 do_test (align, i, -buf_addr - j, BIG_CHAR);
> > > > > +               }
> > > > > +           }
> > > > > +       }
> > > > >      }
> > > > >  }
> > > > >
> > > > > diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > > > index 0593fb303b..b9b58ef599 100644
> > > > > --- a/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > > > +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
> > > > > @@ -544,14 +544,11 @@ 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
> > > > >
> > > > > --
> > > > > 2.34.1
> > > > >
> > > >
> > > > LGTM.
> > > >
> > > > Thanks.
> > > >
> > > > --
> > > > H.J.
> > >
> > > I would like to backport this patch to affected release branches  from
> > > 2.36 to 2.33.
> > >
> > > Any comments/suggestions or objections on this.
> > >
> >
> > OK.
> >
> > Thanks.
> >
> >
> > --
> > H.J.
>
> Just ran testing from 2.32 to 2.26. All of them have this issue.
>
> Ok for 2.32 to 2.26 branches?
>
> --Sunil

Let's stop at 2.28.
diff mbox series

Patch

diff --git a/string/test-strnlen.c b/string/test-strnlen.c
index 4a9375112a..5cbaf4b734 100644
--- a/string/test-strnlen.c
+++ b/string/test-strnlen.c
@@ -73,7 +73,7 @@  do_test (size_t align, size_t len, size_t maxlen, int max_char)
 {
   size_t i;
 
-  align &= 63;
+  align &= (getpagesize () / sizeof (CHAR) - 1);
   if ((align + len) * sizeof (CHAR) >= page_size)
     return;
 
@@ -90,38 +90,50 @@  do_test (size_t align, size_t len, size_t maxlen, int max_char)
 static void
 do_overflow_tests (void)
 {
-  size_t i, j, len;
+  size_t i, j, al_idx, repeats, len;
   const size_t one = 1;
   uintptr_t buf_addr = (uintptr_t) buf1;
+  const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 };
 
-  for (i = 0; i < 750; ++i)
+  for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]);
+       al_idx++)
     {
-      do_test (1, i, SIZE_MAX, BIG_CHAR);
-
-      do_test (0, i, SIZE_MAX - i, BIG_CHAR);
-      do_test (0, i, i - buf_addr, BIG_CHAR);
-      do_test (0, i, -buf_addr - i, BIG_CHAR);
-      do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
-      do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
-
-      len = 0;
-      for (j = 8 * sizeof(size_t) - 1; j ; --j)
-        {
-          len |= one << j;
-          do_test (0, i, len - i, BIG_CHAR);
-          do_test (0, i, len + i, BIG_CHAR);
-          do_test (0, i, len - buf_addr - i, BIG_CHAR);
-          do_test (0, i, len - buf_addr + i, BIG_CHAR);
-
-          do_test (0, i, ~len - i, BIG_CHAR);
-          do_test (0, i, ~len + i, BIG_CHAR);
-          do_test (0, i, ~len - buf_addr - i, BIG_CHAR);
-          do_test (0, i, ~len - buf_addr + i, BIG_CHAR);
-
-          do_test (0, i, -buf_addr, BIG_CHAR);
-          do_test (0, i, j - buf_addr, BIG_CHAR);
-          do_test (0, i, -buf_addr - j, BIG_CHAR);
-        }
+      for (repeats = 0; repeats < 2; ++repeats)
+	{
+	  size_t align = repeats ? (getpagesize () - alignments[al_idx])
+				 : alignments[al_idx];
+	  align /= sizeof (CHAR);
+	  for (i = 0; i < 750; ++i)
+	    {
+	      do_test (align, i, SIZE_MAX, BIG_CHAR);
+
+	      do_test (align, i, SIZE_MAX - i, BIG_CHAR);
+	      do_test (align, i, i - buf_addr, BIG_CHAR);
+	      do_test (align, i, -buf_addr - i, BIG_CHAR);
+	      do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR);
+	      do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR);
+
+	      len = 0;
+	      for (j = 8 * sizeof (size_t) - 1; j; --j)
+		{
+		  len |= one << j;
+		  do_test (align, i, len, BIG_CHAR);
+		  do_test (align, i, len - i, BIG_CHAR);
+		  do_test (align, i, len + i, BIG_CHAR);
+		  do_test (align, i, len - buf_addr - i, BIG_CHAR);
+		  do_test (align, i, len - buf_addr + i, BIG_CHAR);
+
+		  do_test (align, i, ~len - i, BIG_CHAR);
+		  do_test (align, i, ~len + i, BIG_CHAR);
+		  do_test (align, i, ~len - buf_addr - i, BIG_CHAR);
+		  do_test (align, i, ~len - buf_addr + i, BIG_CHAR);
+
+		  do_test (align, i, -buf_addr, BIG_CHAR);
+		  do_test (align, i, j - buf_addr, BIG_CHAR);
+		  do_test (align, i, -buf_addr - j, BIG_CHAR);
+		}
+	    }
+	}
     }
 }
 
diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
index 0593fb303b..b9b58ef599 100644
--- a/sysdeps/x86_64/multiarch/strlen-avx2.S
+++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
@@ -544,14 +544,11 @@  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