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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 944F3C48BC2 for ; Mon, 21 Jun 2021 16:41:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80F2C60698 for ; Mon, 21 Jun 2021 16:41:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233160AbhFUQnP (ORCPT ); Mon, 21 Jun 2021 12:43:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:33914 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233287AbhFUQjl (ORCPT ); Mon, 21 Jun 2021 12:39:41 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DD37D61437; Mon, 21 Jun 2021 16:30:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624293002; bh=AlZxMTimW7gPGtuJO0fGZ+pM38Qe9O+6Uqp/tfm3fPc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2EaigIEWp7jEY3JwzWXVEUxF+zW2+l4tV9nrgKnt19S8x/x6E8/8gqw7qeQd/O2mK FijQsPUfPy6boIPeC+viTyFsdkDDbzE/7doMUNJlC6qnmIo7nYW+6f9Z6l8CExYQaa gHMeJ1GevuBA6DVjua7+50g1P1gftwQlv+UcAHWI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paolo Abeni , "David S. Miller" , Sasha Levin , Kaustubh Pandey Subject: [PATCH 5.12 029/178] udp: fix race between close() and udp_abort() Date: Mon, 21 Jun 2021 18:14:03 +0200 Message-Id: <20210621154922.876383898@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210621154921.212599475@linuxfoundation.org> References: <20210621154921.212599475@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paolo Abeni [ Upstream commit a8b897c7bcd47f4147d066e22cc01d1026d7640e ] Kaustubh reported and diagnosed a panic in udp_lib_lookup(). The root cause is udp_abort() racing with close(). Both racing functions acquire the socket lock, but udp{v6}_destroy_sock() release it before performing destructive actions. We can't easily extend the socket lock scope to avoid the race, instead use the SOCK_DEAD flag to prevent udp_abort from doing any action when the critical race happens. Diagnosed-and-tested-by: Kaustubh Pandey Fixes: 5d77dca82839 ("net: diag: support SOCK_DESTROY for UDP sockets") Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/udp.c | 10 ++++++++++ net/ipv6/udp.c | 3 +++ 2 files changed, 13 insertions(+) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index c586a6bb8c6d..3dd340679d09 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2576,6 +2576,9 @@ void udp_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); bool slow = lock_sock_fast(sk); + + /* protects from races with udp_abort() */ + sock_set_flag(sk, SOCK_DEAD); udp_flush_pending_frames(sk); unlock_sock_fast(sk, slow); if (static_branch_unlikely(&udp_encap_needed_key)) { @@ -2826,10 +2829,17 @@ int udp_abort(struct sock *sk, int err) { lock_sock(sk); + /* udp{v6}_destroy_sock() sets it under the sk lock, avoid racing + * with close() + */ + if (sock_flag(sk, SOCK_DEAD)) + goto out; + sk->sk_err = err; sk->sk_error_report(sk); __udp_disconnect(sk, 0); +out: release_sock(sk); return 0; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index d25e5a9252fd..29288f134d7a 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1597,6 +1597,9 @@ void udpv6_destroy_sock(struct sock *sk) { struct udp_sock *up = udp_sk(sk); lock_sock(sk); + + /* protects from races with udp_abort() */ + sock_set_flag(sk, SOCK_DEAD); udp_v6_flush_pending_frames(sk); release_sock(sk); -- 2.30.2