malloc: 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:

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

	[BZ #15856]
	* malloc/malloc.c (__libc_valloc): Check the value of bytes
	does not overflow.

2 files changed, 14 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index edf1a9cc27..bd8deafc6c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2013-09-11  Will Newton  <will.newton@linaro.org>
 
+	[BZ #15856]
+	* malloc/malloc.c (__libc_valloc): Check the value of bytes
+	does not overflow.
+
+2013-09-11  Will Newton  <will.newton@linaro.org>
+
 	[BZ #15855]
 	* malloc/malloc.c (__libc_pvalloc): Check the value of bytes
 	does not overflow.
diff --git a/malloc/malloc.c b/malloc/malloc.c
index ee89a67dbc..d5dacbf5bc 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3073,8 +3073,14 @@ __libc_valloc(size_t bytes)
 
   size_t pagesz = GLRO(dl_pagesize);
 
-  __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
-					const __malloc_ptr_t)) =
+  /* Check for overflow.  */
+  if (bytes > SIZE_MAX - pagesz - MINSIZE)
+    {
+      __set_errno (ENOMEM);
+      return 0;
+    }
+
+  void *(*hook) (size_t, size_t, const void *) =
     force_reg (__memalign_hook);
   if (__builtin_expect (hook != NULL, 0))
     return (*hook)(pagesz, bytes, RETURN_ADDRESS (0));