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.

(cherry picked from commit b73ed247781d533628b681f57257dc85882645d3)

2 files changed, 13 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index bf6d83790c..fbfae9af3b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 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]
 	* malloc/malloc.c (__libc_valloc): Check the value of bytes
 	does not overflow.
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 31e2dfad91..ebbe86dc7c 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3015,6 +3015,13 @@ __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;