Fix race in free() of fastbin chunk: BZ #15073

Perform sanity check only if we have_lock.  Due to lockless nature of fastbins
we need to be careful derefencing pointers to fastbin entries (chunksize(old)
in this case) in multithreaded environments.

The fix is to add have_lock to the if-condition checks.  The rest of the patch
only makes code more readable.

	* malloc/malloc.c (_int_free): Perform sanity check only if we
	have_lock.

Conflicts:

	ChangeLog
	NEWS

1 files changed, 7 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 1e5efa7..74d4330 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-01-04  Maxim Kuvyrkov  <maxim@kugelworks.com>
+	    Ondřej Bílka  <neleai@seznam.cz>
+
+	[BZ #15073]
+	* malloc/malloc.c (_int_free): Perform sanity check only if we
+        have_lock.
+
 2013-11-11  David S. Miller  <davem@davemloft.net>
 
 	[BZ #16150]