[PATCH v2 1/7] malloc: Add check for top size corruption.

[Istvan Kurucsai <pistukem at gmail dot com>]

Ensure that the size of top is below av->system_mem.

    * malloc/malloc.c (_int_malloc): Check top size.
---
 malloc/malloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/malloc/malloc.c b/malloc/malloc.c
index f94d51c..4a30c42 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4078,6 +4078,10 @@ _int_malloc (mstate av, size_t bytes)
 
       if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
         {
+          if (__glibc_unlikely ((unsigned long) (size) > 
+                                (unsigned long) (av->system_mem)))
+            malloc_printerr("malloc(): corrupted top chunk");
+
           remainder_size = size - nb;
           remainder = chunk_at_offset (victim, nb);
           av->top = remainder;
-- 
2.7.4