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

["H.J. Lu" <hjl.tools@gmail.com>]

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?

Thanks.

-- 
H.J.