From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52F24C433E0 for ; Wed, 20 May 2020 11:46:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 255A220657 for ; Wed, 20 May 2020 11:46:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726566AbgETLp7 (ORCPT ); Wed, 20 May 2020 07:45:59 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:65407 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726224AbgETLp7 (ORCPT ); Wed, 20 May 2020 07:45:59 -0400 Received: from fsav109.sakura.ne.jp (fsav109.sakura.ne.jp [27.133.134.236]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 04KBjaVW034253; Wed, 20 May 2020 20:45:36 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav109.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav109.sakura.ne.jp); Wed, 20 May 2020 20:45:36 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav109.sakura.ne.jp) Received: from localhost.localdomain (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 04KBjU9E034122 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 20 May 2020 20:45:36 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) From: Tetsuo Handa To: Jon Maloy , Ying Xue Cc: netdev@vger.kernel.org, Tetsuo Handa Subject: [PATCH] tipc: Disable preemption when calling send_msg method. Date: Wed, 20 May 2020 20:45:29 +0900 Message-Id: <20200520114529.3433-1-penguin-kernel@I-love.SAKURA.ne.jp> X-Mailer: git-send-email 2.18.2 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org syzbot is reporting that tipc_udp_send_msg() is calling dst_cache_get() without preemption disabled [1]. Since b->media->send_msg() is called with RCU lock already held, we can also disable preemption at that point. [1] https://syzkaller.appspot.com/bug?id=dc6352b92862eb79373fe03fdf9af5928753e057 Reported-by: syzbot+1a68504d96cd17b33a05@syzkaller.appspotmail.com Signed-off-by: Tetsuo Handa --- net/tipc/bearer.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c index 34ca7b789eba..e5cf91665881 100644 --- a/net/tipc/bearer.c +++ b/net/tipc/bearer.c @@ -516,6 +516,7 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id, struct tipc_msg *hdr = buf_msg(skb); struct tipc_bearer *b; + preempt_disable(); rcu_read_lock(); b = bearer_get(net, bearer_id); if (likely(b && (test_bit(0, &b->up) || msg_is_reset(hdr)))) { @@ -528,6 +529,7 @@ void tipc_bearer_xmit_skb(struct net *net, u32 bearer_id, kfree_skb(skb); } rcu_read_unlock(); + preempt_enable(); } /* tipc_bearer_xmit() -send buffer to destination over bearer @@ -543,6 +545,7 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id, if (skb_queue_empty(xmitq)) return; + preempt_disable(); rcu_read_lock(); b = bearer_get(net, bearer_id); if (unlikely(!b)) @@ -560,6 +563,7 @@ void tipc_bearer_xmit(struct net *net, u32 bearer_id, } } rcu_read_unlock(); + preempt_enable(); } /* tipc_bearer_bc_xmit() - broadcast buffers to all destinations @@ -574,6 +578,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id, struct sk_buff *skb, *tmp; struct tipc_msg *hdr; + preempt_disable(); rcu_read_lock(); b = bearer_get(net, bearer_id); if (unlikely(!b || !test_bit(0, &b->up))) @@ -591,6 +596,7 @@ void tipc_bearer_bc_xmit(struct net *net, u32 bearer_id, b->media->send_msg(net, skb, b, dst); } rcu_read_unlock(); + preempt_enable(); } /** -- 2.18.2