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 B6F6EC49ECB 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 984076199B for ; Mon, 28 Jun 2021 15:19:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238241AbhF1PUr (ORCPT ); Mon, 28 Jun 2021 11:20:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:36472 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234548AbhF1O62 (ORCPT ); Mon, 28 Jun 2021 10:58:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B7AC561D53; Mon, 28 Jun 2021 14:40:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624891232; bh=MUjuC7GdNBhIx6fuR3fimo9iS7oV/GVPhXSEhlgaFJI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l1nh3RephgbtCYYd/mHx8lEkZTls3Ud7MuoAq01VX3DmcZZSxJIysruQNfkckVbbb l5B9wiE36f4ZxRSTwTiJcMC0sXKGmDmCEFbPAvdu7KWYSW6M07qLGtPVdFB0TQX3jD q8NeQHssCGfZw/SAxjzDq5FuCTRxPckvBWG/BGpHKXKC1qn/Ht2AhCwIjlrA3bpZV8 JLeD0NP9fDMQXtzaATg7PkEdIUT3Go6FlSL58X8UizK5byQXDqsUw0LBlF75E4Afld HEWxPyak8UnZMUWnn8VRjPz9peGEOU1y1lRMv0/NOpsGOO0UafIn/IAUydBoP4pSHQ jJ+li+cCsajeQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , syzbot , "David S . Miller" , Sasha Levin Subject: [PATCH 4.9 31/71] net/af_unix: fix a data-race in unix_dgram_sendmsg / unix_release_sock Date: Mon, 28 Jun 2021 10:39:23 -0400 Message-Id: <20210628144003.34260-32-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: Eric Dumazet [ Upstream commit a494bd642d9120648b06bb7d28ce6d05f55a7819 ] While unix_may_send(sk, osk) is called while osk is locked, it appears unix_release_sock() can overwrite unix_peer() after this lock has been released, making KCSAN unhappy. Changing unix_release_sock() to access/change unix_peer() before lock is released should fix this issue. BUG: KCSAN: data-race in unix_dgram_sendmsg / unix_release_sock write to 0xffff88810465a338 of 8 bytes by task 20852 on cpu 1: unix_release_sock+0x4ed/0x6e0 net/unix/af_unix.c:558 unix_release+0x2f/0x50 net/unix/af_unix.c:859 __sock_release net/socket.c:599 [inline] sock_close+0x6c/0x150 net/socket.c:1258 __fput+0x25b/0x4e0 fs/file_table.c:280 ____fput+0x11/0x20 fs/file_table.c:313 task_work_run+0xae/0x130 kernel/task_work.c:164 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:175 [inline] exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:209 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline] syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff88810465a338 of 8 bytes by task 20888 on cpu 0: unix_may_send net/unix/af_unix.c:189 [inline] unix_dgram_sendmsg+0x923/0x1610 net/unix/af_unix.c:1712 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350 ___sys_sendmsg net/socket.c:2404 [inline] __sys_sendmmsg+0x315/0x4b0 net/socket.c:2490 __do_sys_sendmmsg net/socket.c:2519 [inline] __se_sys_sendmmsg net/socket.c:2516 [inline] __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2516 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0xffff888167905400 -> 0x0000000000000000 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 20888 Comm: syz-executor.0 Not tainted 5.13.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/unix/af_unix.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index bcd6ed6e7e25..8bbaa35937dd 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -534,12 +534,14 @@ static void unix_release_sock(struct sock *sk, int embrion) u->path.mnt = NULL; state = sk->sk_state; sk->sk_state = TCP_CLOSE; + + skpair = unix_peer(sk); + unix_peer(sk) = NULL; + unix_state_unlock(sk); wake_up_interruptible_all(&u->peer_wait); - skpair = unix_peer(sk); - if (skpair != NULL) { if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) { unix_state_lock(skpair); @@ -554,7 +556,6 @@ static void unix_release_sock(struct sock *sk, int embrion) unix_dgram_peer_wake_disconnect(sk, skpair); sock_put(skpair); /* It may now die */ - unix_peer(sk) = NULL; } /* Try to flush out this socket. Throw out buffers at least */ -- 2.30.2