svn commit: r277625 - stable/10/sys/kern

[Xin LI]

Author: delphij
Date: Sat Jan 24 00:27:50 2015
New Revision: 277625
URL: https://svnweb.freebsd.org/changeset/base/277625

Log:
  MFC r276904:
  
  Improve style and fix a possible use-after-free case introduced in r268384
  by reinitializing the 'freestate' pointer after freeing the memory.
  
  Obtained from:	HardenedBSD (71fab80c5dd3034b71a29a61064625018671bbeb)
  PR:		194525
  Submitted by:	Oliver Pinter <oliver.pinter at hardenedbsd.org>

Modified:
  stable/10/sys/kern/kern_lockf.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/kern/kern_lockf.c
==============================================================================
--- stable/10/sys/kern/kern_lockf.c	Sat Jan 24 00:04:34 2015	(r277624)
+++ stable/10/sys/kern/kern_lockf.c	Sat Jan 24 00:27:50 2015	(r277625)
@@ -740,12 +740,13 @@ retry_setlock:
 
 	VI_UNLOCK(vp);
 
-	if (freestate) {
+	if (freestate != NULL) {
 		sx_xlock(&lf_lock_states_lock);
 		LIST_REMOVE(freestate, ls_link);
 		sx_xunlock(&lf_lock_states_lock);
 		sx_destroy(&freestate->ls_lock);
 		free(freestate, M_LOCKF);
+		freestate = NULL;
 	}
 
 	if (error == EDOOFUS) {