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[PATCH 2/7] malloc/malloc.c: Check for integer overflow in valloc.


A large bytes parameter to valloc 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_valloc): 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 7468758..9aecc85 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3046,6 +3046,10 @@ __libc_valloc(size_t bytes)

   size_t pagesz = GLRO(dl_pagesize);

+  /* Check for overflow.  */
+  if (bytes + pagesz + MINSIZE < bytes)
+    return 0;
+
   void *(*hook) (size_t, size_t, const void *) =
     force_reg (__memalign_hook);
   if (__builtin_expect (hook != NULL, 0))
-- 
1.8.1.4


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