From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch net] llc: set SOCK_RCU_FREE in llc_sap_add_socket() Date: Thu, 11 Oct 2018 11:15:13 -0700 Message-ID: <20181011181513.20203-1-xiyou.wangcong@gmail.com> Cc: Cong Wang To: netdev@vger.kernel.org Return-path: Received: from mail-pg1-f196.google.com ([209.85.215.196]:36124 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbeJLBnp (ORCPT ); Thu, 11 Oct 2018 21:43:45 -0400 Received: by mail-pg1-f196.google.com with SMTP id f18-v6so4565421pgv.3 for ; Thu, 11 Oct 2018 11:15:24 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: WHen an llc sock is added into the sk_laddr_hash of an llc_sap, it is not marked with SOCK_RCU_FREE. This causes that the sock could be freed while it is still being read by __llc_lookup_established() with RCU read lock. sock is refcounted, but with RCU read lock, nothing prevents the readers getting a zero refcnt. Fix it by setting SOCK_RCU_FREE in llc_sap_add_socket(). Reported-by: syzbot+11e05f04c15e03be5254@syzkaller.appspotmail.com Signed-off-by: Cong Wang --- net/llc/llc_conn.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c index c0ac522b48a1..4ff89cb7c86f 100644 --- a/net/llc/llc_conn.c +++ b/net/llc/llc_conn.c @@ -734,6 +734,7 @@ void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk) llc_sk(sk)->sap = sap; spin_lock_bh(&sap->sk_lock); + sock_set_flag(sk, SOCK_RCU_FREE); sap->sk_count++; sk_nulls_add_node_rcu(sk, laddr_hb); hlist_add_head(&llc->dev_hash_node, dev_hb); -- 2.14.4