malloc: Print error when oldsize is not equal to the current size.

This is used to detect errors early.  The read of the oldsize is
not protected by any lock, so check this value to avoid causing
bigger mistakes.

Reviewed-by: DJ Delorie <dj@redhat.com>

diff --git a/malloc/malloc.c b/malloc/malloc.c
index bfe19557379268eb72991b4c692a4fb8c6adabe8..67ac661256eb4a892f2818bca11eb437eeffc0e8 100644 (file)
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -4803,7 +4803,8 @@ _int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
 
   /* oldmem size */
   if (__builtin_expect (chunksize_nomask (oldp) <= CHUNK_HDR_SZ, 0)
-      || __builtin_expect (oldsize >= av->system_mem, 0))
+      || __builtin_expect (oldsize >= av->system_mem, 0)
+      || __builtin_expect (oldsize != chunksize (oldp), 0))
     malloc_printerr ("realloc(): invalid old size");
 
   check_inuse_chunk (av, oldp);