String: Add overflow tests for strnlen, memchr, and strncat [BZ #27974]

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.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

1 files changed, 36 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;
@@ -108,6 +108,38 @@ do_test (size_t align, size_t pos, size_t len, size_t n, int seek_char)
 }
 
 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)
 {
   size_t i, j, n, align, pos, len;
@@ -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;
 }