malloc: Fix for infinite loop in memalign/posix_memalign.

A very large alignment argument passed to mealign/posix_memalign
causes _int_memalign to enter an infinite loop. Limit the maximum
alignment value to the maximum representable power of two to
prevent this from happening.

Changelog:

2013-10-30  Will Newton  <will.newton@linaro.org>

	[BZ #16038]
	* malloc/hooks.c (memalign_check): Limit alignment to the
	maximum representable power of two.
	* malloc/malloc.c (__libc_memalign): Likewise.
	* malloc/tst-memalign.c (do_test): Add test for very
	large alignment values.
	* malloc/tst-posix_memalign.c (do_test): Likewise.

1 files changed, 15 insertions, 0 deletions

diff --git a/malloc/tst-memalign.c b/malloc/tst-memalign.c
index 1c59752483..cf48e7ed1f 100644
--- a/malloc/tst-memalign.c
+++ b/malloc/tst-memalign.c
@@ -70,6 +70,21 @@ do_test (void)
 
   free (p);
 
+  errno = 0;
+
+  /* Test to expose integer overflow in malloc internals from BZ #16038.  */
+  p = memalign (-1, pagesize);
+
+  save = errno;
+
+  if (p != NULL)
+    merror ("memalign (-1, pagesize) succeeded.");
+
+  if (p == NULL && save != EINVAL)
+    merror ("memalign (-1, pagesize) errno is not set correctly");
+
+  free (p);
+
   /* A zero-sized allocation should succeed with glibc, returning a
      non-NULL value.  */
   p = memalign (sizeof (void *), 0);