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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 50D6EC49EA3 for ; Mon, 28 Jun 2021 15:19:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 215156197F for ; Mon, 28 Jun 2021 15:19:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237587AbhF1PT5 (ORCPT ); Mon, 28 Jun 2021 11:19:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:60356 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237001AbhF1O4e (ORCPT ); Mon, 28 Jun 2021 10:56:34 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 66F9961C91; Mon, 28 Jun 2021 14:40:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624891224; bh=aUeuIH1sfzJkc/v+yS8bwKEvd50D9xe6Sqf8nR1MWGc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=m7yRS8Nmz/XRSwwjB+UQQPuz73IR4wCdQns/cOeW2ym0YYDc16ZHhpwEiJJJvJWXq pgR95K3EHx1OF+ZIm1SnIvjQbX+EFTmce71Pfy/zv5E9NbHTnxa5mRhAth+Af8YSt/ /dC/dPjHy/BCXO5RFL949Z0rHnnl3VXsF62vAUPe5dDPTQWESPWQ821NMJHuEtzOAG iqfqM5svgHzRTwWTG7kI54N9iqTZCIRbmUDM+6bQWZwTZDnR3iqxIIKXMZ2PCGw242 G64EXYnQp7zVr3pPjS6AhOhVjdd3NtdyeXELZZnzHkjPX8wYs00SB3cqCi0k/FrHKi TX5YEAdeHhBFg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Paolo Abeni , Kaustubh Pandey , "David S . Miller" , Sasha Levin Subject: [PATCH 4.9 21/71] udp: fix race between close() and udp_abort() Date: Mon, 28 Jun 2021 10:39:13 -0400 Message-Id: <20210628144003.34260-22-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210628144003.34260-1-sashal@kernel.org> References: <20210628144003.34260-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.9.274-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.9.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.9.274-rc1 X-KernelTest-Deadline: 2021-06-30T14:39+00:00 X-stable: review X-Patchwork-Hint: Ignore 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 18a1a4890c5f..79249a44e4a3 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1998,6 +1998,9 @@ 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_key_false(&udp_encap_needed) && up->encap_type) { @@ -2228,10 +2231,17 @@ 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 1ad84e18c03b..3a876a2fdd82 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1325,6 +1325,9 @@ 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