[v2,BZ,#15856] malloc: Check for integer overflow in valloc.

Message ID 521327D4.7020006@linaro.org
State Superseded
Headers show

Commit Message

Will Newton Aug. 20, 2013, 8:24 a.m.
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>

	[BZ #15856]
	* malloc/malloc.c (__libc_valloc): Check the value of bytes
	does not overflow.
---
 malloc/malloc.c | 4 ++++
 1 file changed, 4 insertions(+)

Changes in v2:
 - Add BZ number

Comments

Will Newton Sept. 9, 2013, 8:25 a.m. | #1
On 20 August 2013 09:24, Will Newton <will.newton@linaro.org> wrote:
>
> 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>
>
>         [BZ #15856]
>         * malloc/malloc.c (__libc_valloc): Check the value of bytes
>         does not overflow.
> ---
>  malloc/malloc.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> Changes in v2:
>  - Add BZ number

Ping?

Patch

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))