malloc: Check for integer overflow in memalign.

A large bytes parameter to memalign could cause an integer overflow
and corrupt allocator internals. Check the overflow does not occur
before continuing with the allocation.

ChangeLog:

2013-09-11  Will Newton  <will.newton@linaro.org>

	[BZ #15857]
	* malloc/malloc.c (__libc_memalign): Check the value of bytes
	does not overflow.

diff --git a/ChangeLog b/ChangeLog
index bd8deafc6cad51f2761e292256301c1ee33e550f..1669b71cad3af14d210d8ee484390ba22165e705 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-09-11  Will Newton  <will.newton@linaro.org>
+
+       [BZ #15857]
+       * malloc/malloc.c (__libc_memalign): Check the value of bytes
+       does not overflow.
+
 2013-09-11  Will Newton  <will.newton@linaro.org>
 
        [BZ #15856]

diff --git a/malloc/malloc.c b/malloc/malloc.c
index d5dacbf5bc3a899a8b20869b33528bac66dd2e6b..d04cae8f70b3918a3f7fe87cb27fc1104b99ced2 100644 (file)
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3030,6 +3030,13 @@ __libc_memalign(size_t alignment, size_t bytes)
   /* Otherwise, ensure that it is at least a minimum chunk size */
   if (alignment <  MINSIZE) alignment = MINSIZE;
 
+  /* Check for overflow.  */
+  if (bytes > SIZE_MAX - alignment - MINSIZE)
+    {
+      __set_errno (ENOMEM);
+      return 0;
+    }
+
   arena_get(ar_ptr, bytes + alignment + MINSIZE);
   if(!ar_ptr)
     return 0;