[PATCH 3/7] malloc/malloc.c: Check for integer overflow in memalign.

[Will Newton]

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:

2013-08-16  Will Newton  <will.newton@linaro.org>

    * malloc/malloc.c (__libc_memalign): Check the value of bytes
    does not overflow.
---
 malloc/malloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 9aecc85..8c1aab8 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3015,6 +3015,10 @@ __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 + alignment + MINSIZE < bytes)
+    return 0;
+
   arena_get(ar_ptr, bytes + alignment + MINSIZE);
   if(!ar_ptr)
     return 0;
-- 
1.8.1.4