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.

diff --git a/ChangeLog b/ChangeLog
index 9997c1cae53b1b8dd3ee5cd46e1b024c731e812c..edf1a9cc27f2086eeafbebadc3304128cfad74be 100644 (file)
--- 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.
+
 2013-08-16  Florian Weimer  <fweimer@redhat.com>
 
        [BZ #14699]

diff --git a/malloc/malloc.c b/malloc/malloc.c
index 28039b4720dfa973a9577ca35a8f78e2ade65fb4..ee89a67dbc53c1f9f54b92a5b05a5c531ab5ec5b 100644 (file)
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -3119,6 +3119,13 @@ __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;
+    }
+
   __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
                                        const __malloc_ptr_t)) =
     force_reg (__memalign_hook);