kmemleak: Do not return a pointer to an object that kmemleak did not get

commit 52c3ce4ec5601ee383a14f1485f6bac7b278896e upstream.

The kmemleak_seq_next() function tries to get an object (and increment
its use count) before returning it. If it could not get the last object
during list traversal (because it may have been freed), the function
should return NULL rather than a pointer to such object that it did not
get.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 5b069e4f5e485ac8f5906c4a0cad7dbdeef75f7e..c1825863625ac83e3fe29e7531bf560b8f75dd6c 100644 (file)
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1369,9 +1369,12 @@ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
        ++(*pos);
 
        list_for_each_continue_rcu(n, &object_list) {
-               next_obj = list_entry(n, struct kmemleak_object, object_list);
-               if (get_object(next_obj))
+               struct kmemleak_object *obj =
+                       list_entry(n, struct kmemleak_object, object_list);
+               if (get_object(obj)) {
+                       next_obj = obj;
                        break;
+               }
        }
 
        put_object(prev_obj);