From: Hoang Le <hoang.h.le@dektech.com.au>
Date: Fri, 13 Mar 2020 03:18:03 +0000 (+0700)
Subject: tipc: add NULL pointer check to prevent kernel oops
X-Git-Tag: v5.15~4200^2~163
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=746a1eda682cb7b5cd22f1b437da2121af64fbfe;p=platform%2Fkernel%2Flinux-starfive.git

tipc: add NULL pointer check to prevent kernel oops

Calling:
tipc_node_link_down()->
   - tipc_node_write_unlock()->tipc_mon_peer_down()
   - tipc_mon_peer_down()
  just after disabling bearer could be caused kernel oops.

Fix this by adding a sanity check to make sure valid memory
access.

Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c
index 58708b4..6dce2ab 100644
--- a/net/tipc/monitor.c
+++ b/net/tipc/monitor.c
@@ -322,9 +322,13 @@ static void mon_assign_roles(struct tipc_monitor *mon, struct tipc_peer *head)
 void tipc_mon_remove_peer(struct net *net, u32 addr, int bearer_id)
 {
 	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
-	struct tipc_peer *self = get_self(net, bearer_id);
+	struct tipc_peer *self;
 	struct tipc_peer *peer, *prev, *head;
 
+	if (!mon)
+		return;
+
+	self = get_self(net, bearer_id);
 	write_lock_bh(&mon->lock);
 	peer = get_peer(mon, addr);
 	if (!peer)
@@ -407,11 +411,15 @@ exit:
 void tipc_mon_peer_down(struct net *net, u32 addr, int bearer_id)
 {
 	struct tipc_monitor *mon = tipc_monitor(net, bearer_id);
-	struct tipc_peer *self = get_self(net, bearer_id);
+	struct tipc_peer *self;
 	struct tipc_peer *peer, *head;
 	struct tipc_mon_domain *dom;
 	int applied;
 
+	if (!mon)
+		return;
+
+	self = get_self(net, bearer_id);
 	write_lock_bh(&mon->lock);
 	peer = get_peer(mon, addr);
 	if (!peer) {