Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1436457

[PATCH v4] kasan/quarantine: fix bugs on qlist_move_cache()

Show all headers | View raw

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

There are two bugs on qlist_move_cache(). One is that qlist's tail
isn't set properly. curr->next can be NULL since it is singly linked
list and NULL value on tail is invalid if there is one item on qlist.
Another one is that if cache is matched, qlist_put() is called and
it will set curr->next to NULL. It would cause to stop the loop
prematurely.

These problems come from complicated implementation so I'd like to
re-implement it completely. Implementation in this patch is really
simple. Iterate all qlist_nodes and put them to appropriate list.

Unfortunately, I got this bug sometime ago and lose oops message.
But, the bug looks trivial and no need to attach oops.

v4: fix cache size bug s/cache->size/obj_cache->size/
v3: fix build warning

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 mm/kasan/quarantine.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 4973505..b2e1827 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -238,30 +238,23 @@ static void qlist_move_cache(struct qlist_head *from,
 				   struct qlist_head *to,
 				   struct kmem_cache *cache)
 {
-	struct qlist_node *prev = NULL, *curr;
+	struct qlist_node *curr;
 
 	if (unlikely(qlist_empty(from)))
 		return;
 
 	curr = from->head;
+	qlist_init(from);
 	while (curr) {
 		struct qlist_node *qlink = curr;
 		struct kmem_cache *obj_cache = qlink_to_cache(qlink);
 
-		if (obj_cache == cache) {
-			if (unlikely(from->head == qlink)) {
-				from->head = curr->next;
-				prev = curr;
-			} else
-				prev->next = curr->next;
-			if (unlikely(from->tail == qlink))
-				from->tail = curr->next;
-			from->bytes -= cache->size;
-			qlist_put(to, qlink, cache->size);
-		} else {
-			prev = curr;
-		}
 		curr = curr->next;
+
+		if (obj_cache == cache)
+			qlist_put(to, qlink, obj_cache->size);
+		else
+			qlist_put(from, qlink, obj_cache->size);
 	}
 }
 
-- 
1.9.1

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH v4] kasan/quarantine: fix bugs on qlist_move_cache() js1304@gmail.com - 2016-07-04 06:40 +0200
  Re: [PATCH v4] kasan/quarantine: fix bugs on qlist_move_cache() Dmitry Vyukov <dvyukov@google.com> - 2016-07-05 15:30 +0200
  Re: [PATCH v4] kasan/quarantine: fix bugs on qlist_move_cache() Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-07-06 03:00 +0200

csiph-web