[Devel,rh7,15/39] kasan/quarantine: fix bugs on qlist_move_cache()

Submitted by Andrey Ryabinin on Sept. 14, 2017, 4:51 p.m.

Details

Message ID 20170914165156.28876-15-aryabinin@virtuozzo.com
State New
Series "Series without cover letter"
Headers show

Commit Message

Andrey Ryabinin Sept. 14, 2017, 4:51 p.m.
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.

Fixes: 55834c59098d ("mm: kasan: initial memory quarantine implementation")
Link: http://lkml.kernel.org/r/1467766348-22419-1-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Kuthonuzo Luruo <poll.stdin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

https://jira.sw.ru/browse/PSBM-69081
(cherry picked from commit 0ab686d8c8303069e80300663b3be6201a8697fb)
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 mm/kasan/quarantine.c | 29 +++++++++++------------------
 1 file changed, 11 insertions(+), 18 deletions(-)

Patch hide | download patch | download mbox

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 4973505a9bdd..65793f150d1f 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;
+		struct qlist_node *next = curr->next;
+		struct kmem_cache *obj_cache = qlink_to_cache(curr);
+
+		if (obj_cache == cache)
+			qlist_put(to, curr, obj_cache->size);
+		else
+			qlist_put(from, curr, obj_cache->size);
+
+		curr = next;
 	}
 }