Re: [PATCH v1 1/3] String: Add additional overflow tests for strnlen, memchr, and strncat

[Noah Goldstein <goldstein.w.n@gmail.com>]

On Tue, Jun 22, 2021 at 12:19 PM H.J. Lu <hjl.tools@gmail.com> wrote:

> On Tue, Jun 22, 2021 at 8:43 AM Noah Goldstein <goldstein.w.n@gmail.com>
> wrote:
> >
> >
> > On Wed, Jun 9, 2021 at 6:26 PM Noah Goldstein <goldstein.w.n@gmail.com>
> wrote:
> >>
> >>
> >>
> >> On Wed, Jun 9, 2021 at 5:54 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>>
> >>> On Wed, Jun 9, 2021 at 1:53 PM Noah Goldstein <goldstein.w.n@gmail.com>
> wrote:
> >>> >
> >>> > This commit adds tests for a bug in the wide char variant of the
> >>> > functions where the implementation may assume that maxlen for wcsnlen
> >>> > or n for wmemchr/strncat will not overflow when multiplied by
> >>> > sizeof(wchar_t).
> >>> >
> >>> > These tests show the following implementations failing on x86_64:
> >>> >
> >>> > wcsnlen-sse4_1
> >>> > wcsnlen-avx2
> >>> >
> >>> > wmemchr-sse2
> >>> > wmemchr-avx2
> >>> >
> >>> > strncat would fail as well if it where on a system that prefered
> >>> > either of the wcsnlen implementations that failed as it relies on
> >>> > wcsnlen.
> >>>
> >>> Please open a bug report for each standard C function.   We need to
> >>> track them for backporting to release branches.
> >>
> >>
> >> Done: https://sourceware.org/bugzilla/show_bug.cgi?id=27974
> >>
> >>>
> >>>
> >>> Thanks.
> >>>
> >>> > Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
> >>> > ---
> >>> >  string/test-memchr.c  | 39 ++++++++++++++++++++++++---
> >>> >  string/test-strncat.c | 61
> +++++++++++++++++++++++++++++++++++++++++++
> >>> >  string/test-strnlen.c | 33 +++++++++++++++++++++++
> >>> >  3 files changed, 130 insertions(+), 3 deletions(-)
> >>> >
> >>> > diff --git a/string/test-memchr.c b/string/test-memchr.c
> >>> > index 665edc32af..ce964284aa 100644
> >>> > --- a/string/test-memchr.c
> >>> > +++ b/string/test-memchr.c
> >>> > @@ -65,8 +65,8 @@ do_one_test (impl_t *impl, const CHAR *s, int c,
> size_t n, CHAR *exp_res)
> >>> >    CHAR *res = CALL (impl, s, c, n);
> >>> >    if (res != exp_res)
> >>> >      {
> >>> > -      error (0, 0, "Wrong result in function %s %p %p", impl->name,
> >>> > -            res, exp_res);
> >>> > +      error (0, 0, "Wrong result in function %s (%p, %d, %zu) -> %p
> != %p",
> >>> > +             impl->name, s, c, n, res, exp_res);
> >>> >        ret = 1;
> >>> >        return;
> >>> >      }
> >>> > @@ -91,7 +91,7 @@ do_test (size_t align, size_t pos, size_t len,
> size_t n, int seek_char)
> >>> >      }
> >>> >    buf[align + len] = 0;
> >>> >
> >>> > -  if (pos < len)
> >>> > +  if (pos < MIN(n, len))
> >>> >      {
> >>> >        buf[align + pos] = seek_char;
> >>> >        buf[align + len] = -seek_char;
> >>> > @@ -107,6 +107,38 @@ do_test (size_t align, size_t pos, size_t len,
> size_t n, int seek_char)
> >>> >      do_one_test (impl, (CHAR *) (buf + align), seek_char, n,
> result);
> >>> >  }
> >>> >
> >>> > +static void
> >>> > +do_overflow_tests (void)
> >>> > +{
> >>> > +  size_t i, j, len;
> >>> > +  const size_t one = 1;
> >>> > +  uintptr_t buf_addr = (uintptr_t) buf1;
> >>> > +
> >>> > +  for (i = 0; i < 750; ++i)
> >>> > +    {
> >>> > +        do_test (0, i, 751, SIZE_MAX - i, BIG_CHAR);
> >>> > +        do_test (0, i, 751, i - buf_addr, BIG_CHAR);
> >>> > +        do_test (0, i, 751, -buf_addr - i, BIG_CHAR);
> >>> > +        do_test (0, i, 751, SIZE_MAX - buf_addr - i, BIG_CHAR);
> >>> > +        do_test (0, i, 751, 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, 751, len - i, BIG_CHAR);
> >>> > +          do_test (0, i, 751, len + i, BIG_CHAR);
> >>> > +          do_test (0, i, 751, len - buf_addr - i, BIG_CHAR);
> >>> > +          do_test (0, i, 751, len - buf_addr + i, BIG_CHAR);
> >>> > +
> >>> > +          do_test (0, i, 751, ~len - i, BIG_CHAR);
> >>> > +          do_test (0, i, 751, ~len + i, BIG_CHAR);
> >>> > +          do_test (0, i, 751, ~len - buf_addr - i, BIG_CHAR);
> >>> > +          do_test (0, i, 751, ~len - buf_addr + i, BIG_CHAR);
> >>> > +        }
> >>> > +    }
> >>> > +}
> >>> > +
> >>> >  static void
> >>> >  do_random_tests (void)
> >>> >  {
> >>> > @@ -221,6 +253,7 @@ test_main (void)
> >>> >      do_test (page_size / 2 - i, i, i, 1, 0x9B);
> >>> >
> >>> >    do_random_tests ();
> >>> > +  do_overflow_tests ();
> >>> >    return ret;
> >>> >  }
> >>> >
> >>> > diff --git a/string/test-strncat.c b/string/test-strncat.c
> >>> > index 2ef917b820..0ab7541d4e 100644
> >>> > --- a/string/test-strncat.c
> >>> > +++ b/string/test-strncat.c
> >>> > @@ -134,6 +134,66 @@ do_test (size_t align1, size_t align2, size_t
> len1, size_t len2,
> >>> >      }
> >>> >  }
> >>> >
> >>> > +static void
> >>> > +do_overflow_tests (void)
> >>> > +{
> >>> > +  size_t i, j, len;
> >>> > +  const size_t one = 1;
> >>> > +  CHAR *s1, *s2;
> >>> > +  uintptr_t s1_addr;
> >>> > +  s1 = (CHAR *) buf1;
> >>> > +  s2 = (CHAR *) buf2;
> >>> > +  s1_addr = (uintptr_t)s1;
> >>> > + for (j = 0; j < 200; ++j)
> >>> > +      s2[j] = 32 + 23 * j % (BIG_CHAR - 32);
> >>> > + s2[200] = 0;
> >>> > +  for (i = 0; i < 750; ++i) {
> >>> > +    for (j = 0; j < i; ++j)
> >>> > +      s1[j] = 32 + 23 * j % (BIG_CHAR - 32);
> >>> > +    s1[i] = '\0';
> >>> > +
> >>> > +       FOR_EACH_IMPL (impl, 0)
> >>> > +    {
> >>> > +      s2[0] = '\0';
> >>> > +      do_one_test (impl, s2, s1, SIZE_MAX - i);
> >>> > +      s2[0] = '\0';
> >>> > +      do_one_test (impl, s2, s1, i - s1_addr);
> >>> > +      s2[0] = '\0';
> >>> > +      do_one_test (impl, s2, s1, -s1_addr - i);
> >>> > +      s2[0] = '\0';
> >>> > +      do_one_test (impl, s2, s1, SIZE_MAX - s1_addr - i);
> >>> > +      s2[0] = '\0';
> >>> > +      do_one_test (impl, s2, s1, SIZE_MAX - s1_addr + i);
> >>> > +    }
> >>> > +
> >>> > +    len = 0;
> >>> > +    for (j = 8 * sizeof(size_t) - 1; j ; --j)
> >>> > +      {
> >>> > +        len |= one << j;
> >>> > +        FOR_EACH_IMPL (impl, 0)
> >>> > +          {
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, len - i);
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, len + i);
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, len - s1_addr - i);
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, len - s1_addr + i);
> >>> > +
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, ~len - i);
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, ~len + i);
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, ~len - s1_addr - i);
> >>> > +            s2[0] = '\0';
> >>> > +            do_one_test (impl, s2, s1, ~len - s1_addr + i);
> >>> > +          }
> >>> > +      }
> >>> > +  }
> >>> > +}
> >>> > +
> >>> >  static void
> >>> >  do_random_tests (void)
> >>> >  {
> >>> > @@ -316,6 +376,7 @@ test_main (void)
> >>> >      }
> >>> >
> >>> >    do_random_tests ();
> >>> > +  do_overflow_tests ();
> >>> >    return ret;
> >>> >  }
> >>> >
> >>> > diff --git a/string/test-strnlen.c b/string/test-strnlen.c
> >>> > index 920f58e97b..f53e09263f 100644
> >>> > --- a/string/test-strnlen.c
> >>> > +++ b/string/test-strnlen.c
> >>> > @@ -89,6 +89,38 @@ do_test (size_t align, size_t len, size_t maxlen,
> int max_char)
> >>> >      do_one_test (impl, (CHAR *) (buf + align), maxlen, MIN (len,
> maxlen));
> >>> >  }
> >>> >
> >>> > +static void
> >>> > +do_overflow_tests (void)
> >>> > +{
> >>> > +  size_t i, j, len;
> >>> > +  const size_t one = 1;
> >>> > +  uintptr_t buf_addr = (uintptr_t) buf1;
> >>> > +
> >>> > +  for (i = 0; i < 750; ++i)
> >>> > +    {
> >>> > +      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);
> >>> > +        }
> >>> > +    }
> >>> > +}
> >>> > +
> >>> >  static void
> >>> >  do_random_tests (void)
> >>> >  {
> >>> > @@ -283,6 +315,7 @@ test_main (void)
> >>> >    do_random_tests ();
> >>> >    do_page_tests ();
> >>> >    do_page_2_tests ();
> >>> > +  do_overflow_tests ();
> >>> >    return ret;
> >>> >  }
> >>> >
> >>> > --
> >>> > 2.25.1
> >>> >
> >>>
> >>>
> >>> --
> >>> H.J.
> >
> >
> > Ping if we want this in 2.34
>
> Can you repost the patches with BZ# in the commit log?
>

Done. (Not sure why the patch didn't come in as reply to this one but just
posted).

>
> Thanks.
>
> --
> H.J.
>