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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 0FB00C433DF for ; Fri, 22 May 2020 21:46:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4A8820757 for ; Fri, 22 May 2020 21:45:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="qGsmjGwl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731154AbgEVVp6 (ORCPT ); Fri, 22 May 2020 17:45:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731072AbgEVVp6 (ORCPT ); Fri, 22 May 2020 17:45:58 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 424BEC061A0E for ; Fri, 22 May 2020 14:45:58 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id n11so5604386pgl.9 for ; Fri, 22 May 2020 14:45:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=o8IX8NAUnDOEVX6Nk7rJBXYRBqlNgn0ggDradDyA97E=; b=qGsmjGwliRvn4RwyclU/hGYzhG8Q2i7HW1y/nWN0E6ozrlE8NepCk2BEPsjEjF7vD3 xnVg/UdjMejxjD6HR3dPPWFQXc6qMGRlxYT2hSGNfhV4C852/amHqP+lELQvTXdz4UCI MJ4tfsWkHTB5Qbd2Oqk6aZ7AikFvHk79KIm+aE9CZGwEhmKGGt60902AHIHsnkjufXHs H2w9AK5xFAGaEGQKTDr368JZDEkTxR42/uT6K2GKW4oLml8UQD2hXso0mkyU0Uqhuafg YqH4YUqLU8niDDjbHW2aslCTccESgU2EHSbgVgk8mD6qGUXK5BuYtuv0QwcIebddX3x0 hCYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=o8IX8NAUnDOEVX6Nk7rJBXYRBqlNgn0ggDradDyA97E=; b=AZVDhdYAB7SmSUsTGM9tSOMa0iw8Rf5KVky2ZuDuSGMXdNuTWgWvhdKt2bAvI/6bqr bNWHkDzIFnoPs7F9L2gi3ZkmGNdLJL8gRuOrF3hoRZZA5RsU1z+8b3dnA7CSKQU3lV2I yP2N6L8dEVpqGd7CzWbEWCGV1VbPEcXILK3SwiBRtLme/n+chxA4Pa7oiXOtaJ1TXmzn INJiMpFFTqfRj5kJGOy2HsHp1BX24JzIYR5z0k0QUJQg7e3DcgvbccVQk7ycJQdD0Nfz rM0UOTLGgD7uHgsiNAmBNdgvPLMexJPOrAw01yLlob63LCEC2cgEK6Oo+GcTlXUzZnKR qh+w== X-Gm-Message-State: AOAM530vqkXLsseIrE7nWmOYkEFO+FYMrHewVsA/7RuB/HlImhdzXxGo BYFL2G6pa2y+g4Qat6TZE5Tpuq5i X-Google-Smtp-Source: ABdhPJyLZMl2h2n/6v4pPqkXcgmiZbtrKdIgYck3++u6OCq7+xNLOjZcL3DhVNXVrkVZsIQKSxqDsg== X-Received: by 2002:a65:49c9:: with SMTP id t9mr3253894pgs.148.1590183957509; Fri, 22 May 2020 14:45:57 -0700 (PDT) Received: from [192.168.86.235] (c-73-241-150-58.hsd1.ca.comcast.net. [73.241.150.58]) by smtp.gmail.com with ESMTPSA id x7sm7581876pfo.160.2020.05.22.14.45.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 May 2020 14:45:56 -0700 (PDT) Subject: Re: [PATCH] tipc: Disable preemption when calling send_msg method. To: Tetsuo Handa , Jon Maloy , Ying Xue Cc: netdev@vger.kernel.org References: <20200520114529.3433-1-penguin-kernel@I-love.SAKURA.ne.jp> From: Eric Dumazet Message-ID: <5a668c12-4038-1f68-3e17-edcdc66e9e96@gmail.com> Date: Fri, 22 May 2020 14:45:55 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200520114529.3433-1-penguin-kernel@I-love.SAKURA.ne.jp> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/20/20 4:45 AM, Tetsuo Handa wrote: > 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(); > } > > /** > This is wrong, see my patch instead. https://patchwork.ozlabs.org/project/netdev/patch/20200521182958.163436-1-edumazet@google.com/ Thanks.