From: Xin Long lucien.xin@gmail.com
[ Upstream commit 42dec1dbe38239cf91cc1f4df7830c66276ced37 ]
Unlike kfree(p), kfree_rcu(p, rcu) won't do NULL pointer check. When tipc_nametbl_remove_publ returns NULL, the panic below happens:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000068 RIP: 0010:__call_rcu+0x1d/0x290 Call Trace: <IRQ> tipc_publ_notify+0xa9/0x170 [tipc] tipc_node_write_unlock+0x8d/0x100 [tipc] tipc_node_link_down+0xae/0x1d0 [tipc] tipc_node_check_dest+0x3ea/0x8f0 [tipc] ? tipc_disc_rcv+0x2c7/0x430 [tipc] tipc_disc_rcv+0x2c7/0x430 [tipc] ? tipc_rcv+0x6bb/0xf20 [tipc] tipc_rcv+0x6bb/0xf20 [tipc] ? ip_route_input_slow+0x9cf/0xb10 tipc_udp_recv+0x195/0x1e0 [tipc] ? tipc_udp_is_known_peer+0x80/0x80 [tipc] udp_queue_rcv_skb+0x180/0x460 udp_unicast_rcv_skb.isra.56+0x75/0x90 __udp4_lib_rcv+0x4ce/0xb90 ip_local_deliver_finish+0x11c/0x210 ip_local_deliver+0x6b/0xe0 ? ip_rcv_finish+0xa9/0x410 ip_rcv+0x273/0x362
Fixes: 97ede29e80ee ("tipc: convert name table read-write lock to RCU") Reported-by: Li Shuang shuali@redhat.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/tipc/name_distr.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/tipc/name_distr.c +++ b/net/tipc/name_distr.c @@ -284,7 +284,8 @@ static void tipc_publ_purge(struct net * publ->key); }
- kfree_rcu(p, rcu); + if (p) + kfree_rcu(p, rcu); }
void tipc_publ_notify(struct net *net, struct list_head *nsub_list, u32 addr)