From d094c4d5f5c7e1b225e94227ca3f007be3adc4e8 Mon Sep 17 00:00:00 2001
From: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Date: Tue, 24 Jan 2017 13:00:44 +0100
Subject: tipc: add subscription refcount to avoid invalid delete
Until now, the subscribers keep track of the subscriptions using
reference count at subscriber level. At subscription cancel or
subscriber delete, we delete the subscription only if the timer
was pending for the subscription. This approach is incorrect as:
1. del_timer() is not SMP safe, if on CPU0 the check for pending
timer returns true but CPU1 might schedule the timer callback
thereby deleting the subscription. Thus when CPU0 is scheduled,
it deletes an invalid subscription.
2. We export tipc_subscrp_report_overlap(), which accesses the
subscription pointer multiple times. Meanwhile the subscription
timer can expire thereby freeing the subscription and we might
continue to access the subscription pointer leading to memory
violations.
In this commit, we introduce subscription refcount to avoid deleting
an invalid subscription.
Reported-and-Tested-by: John Thompson <thompa.atl@gmail.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Parthasarathy Bhuvaragan <parthasarathy.bhuvaragan@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/tipc/subscr.h | 1 +
1 file changed, 1 insertion(+)
(limited to 'net/tipc/subscr.h')
diff --git a/net/tipc/subscr.h b/net/tipc/subscr.h
index be60103082c9..ffdc214c117a 100644
--- a/net/tipc/subscr.h
+++ b/net/tipc/subscr.h
@@ -57,6 +57,7 @@ struct tipc_subscriber;
* @evt: template for events generated by subscription
*/
struct tipc_subscription {
+ struct kref kref;
struct tipc_subscriber *subscriber;
struct net *net;
struct timer_list timer;
--
cgit v1.2.3