malloc: Check for integer overflow in pvalloc.

A large bytes parameter to pvalloc 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 #15855]
	* malloc/malloc.c (__libc_pvalloc): Check the value of bytes
	does not overflow.

2 files changed, 13 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 21ff1b8d2a..b95693f07f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-09-11  Will Newton  <will.newton@linaro.org>
+
+	[BZ #15855]
+	* malloc/malloc.c (__libc_pvalloc): Check the value of bytes
+	does not overflow.
+
 2013-09-10   Ondřej Bílka  <neleai@seznam.cz>
 
 	* sysdeps/ieee754/dbl-64/e_j0.c: Remove DO_NOT_USE_THIS conditionals.
diff --git a/malloc/malloc.c b/malloc/malloc.c
index dd295f522c..7f43ba3b8f 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3082,6 +3082,13 @@ __libc_pvalloc(size_t bytes)
   size_t page_mask = GLRO(dl_pagesize) - 1;
   size_t rounded_bytes = (bytes + page_mask) & ~(page_mask);
 
+  /* Check for overflow.  */
+  if (bytes > SIZE_MAX - 2*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))