Commit 0ab686d8 authored Jul 14, 2016 by Joonsoo Kim Committed by Linus Torvalds Jul 15, 2016

kasan/quarantine: fix bugs on qlist_move_cache()

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: 55834c59 ("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>

parent 12cb22bb

mm/kasan/quarantine.c

+11 −18

Original line number	Diff line number	Diff line
		@@ -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;
		}
		}

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