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.

diff --git a/ChangeLog b/ChangeLog
index b95693f..f2d2154 100644 (file)
--- 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 7f43ba3..3148c5f 100644 (file)
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3046,6 +3046,13 @@ __libc_valloc(size_t bytes)
 
   size_t pagesz = GLRO(dl_pagesize);
 
+  /* 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))