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 c1d5867543e4da3962b8ee36bf191f89f6870e99..aacee45616fc44792f768135abc99dd6f429f003 100644 (file)
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1414,9 +1414,12 @@ 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);