From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-fw-52003.amazon.com (smtp-fw-52003.amazon.com [52.119.213.152]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D287E12DD88; Fri, 10 May 2024 04:50:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.119.213.152 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715316609; cv=none; b=N4A/yqqv2uMN6CSMLMOYDJqZvrvwjB3BEalCNHQ8nDpvnYQiqAsOdG8xXTYUXl3UGtfI/pnAYwStEXTvMHOUaIoDZ6c566t4wjU5mNJHUEdZiztqt8/1GN4otGNeFe3BonQm2WGg+kuGbYtW1/ThrrNPvel7QxsilY2L5ownPsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715316609; c=relaxed/simple; bh=Ojbxz06eYniGbmSWyknhMjXnkbDq+DPs55HNM0uCzNA=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=gBtTwrNuQ3BUulzk3lz7HdGs/hqCmvwve731ch91oFKgVDOYhZWDwSIvCcEmCk85uwGPcm1IXIM/tyCMtKz9wiHf+4svpFGGcMi/dfjRtFyOh8xy0NN6enqnuP2LiK5Et66Z6rTvnC9S2H0L1hlBaj27F90P0lZHvHm40h1j7q8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=WXcxe161; arc=none smtp.client-ip=52.119.213.152 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="WXcxe161" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1715316608; x=1746852608; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=5bl0Zifhqq7E3SoEKYbnz8ntYa90jVZRoq1CV9kYkGQ=; b=WXcxe1613DL0S0dOLHM0bGjFyXt73PzCBvTso9U9+QSEJT8F+LJ21UmL MEHiYv4FsugpiBnpasaQ+XVYSEjNKmYeaZFHGKBT74tDSzNDvBnujRkml dr2Lw4gS1s5DglYH86aVSna5bSOJL7juzkhGSWdZ+hYT3UiHGW3H20Vd5 g=; X-IronPort-AV: E=Sophos;i="6.08,150,1712620800"; d="scan'208";a="657824590" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.43.8.6]) by smtp-border-fw-52003.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 May 2024 04:50:05 +0000 Received: from EX19MTAUWC002.ant.amazon.com [10.0.7.35:1742] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.12.40:2525] with esmtp (Farcaster) id 2c3c20f3-af69-4b47-b2fb-8052ca477e74; Fri, 10 May 2024 04:50:04 +0000 (UTC) X-Farcaster-Flow-ID: 2c3c20f3-af69-4b47-b2fb-8052ca477e74 Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWC002.ant.amazon.com (10.250.64.143) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Fri, 10 May 2024 04:50:03 +0000 Received: from 88665a182662.ant.amazon.com.com (10.119.0.5) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Fri, 10 May 2024 04:49:59 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , , , , , , , Subject: Re: [PATCH net v2] af_unix: Fix data races in unix_release_sock/unix_stream_sendmsg Date: Fri, 10 May 2024 13:49:48 +0900 Message-ID: <20240510044948.26074-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240509081459.2807828-1-leitao@debian.org> References: <20240509081459.2807828-1-leitao@debian.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D040UWA002.ant.amazon.com (10.13.139.113) To EX19D004ANA001.ant.amazon.com (10.37.240.138) From: Breno Leitao Date: Thu, 9 May 2024 01:14:46 -0700 > A data-race condition has been identified in af_unix. In one data path, > the write function unix_release_sock() atomically writes to > sk->sk_shutdown using WRITE_ONCE. However, on the reader side, > unix_stream_sendmsg() does not read it atomically. Consequently, this > issue is causing the following KCSAN splat to occur: > > BUG: KCSAN: data-race in unix_release_sock / unix_stream_sendmsg > > write (marked) to 0xffff88867256ddbb of 1 bytes by task 7270 on cpu 28: > unix_release_sock (net/unix/af_unix.c:640) > unix_release (net/unix/af_unix.c:1050) > sock_close (net/socket.c:659 net/socket.c:1421) > __fput (fs/file_table.c:422) > __fput_sync (fs/file_table.c:508) > __se_sys_close (fs/open.c:1559 fs/open.c:1541) > __x64_sys_close (fs/open.c:1541) > x64_sys_call (arch/x86/entry/syscall_64.c:33) > do_syscall_64 (arch/x86/entry/common.c:?) > entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > > read to 0xffff88867256ddbb of 1 bytes by task 989 on cpu 14: > unix_stream_sendmsg (net/unix/af_unix.c:2273) > __sock_sendmsg (net/socket.c:730 net/socket.c:745) > ____sys_sendmsg (net/socket.c:2584) > __sys_sendmmsg (net/socket.c:2638 net/socket.c:2724) > __x64_sys_sendmmsg (net/socket.c:2753 net/socket.c:2750 net/socket.c:2750) > x64_sys_call (arch/x86/entry/syscall_64.c:33) > do_syscall_64 (arch/x86/entry/common.c:?) > entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) > > value changed: 0x01 -> 0x03 > > The line numbers are related to commit dd5a440a31fa ("Linux 6.9-rc7"). > > Commit e1d09c2c2f57 ("af_unix: Fix data races around sk->sk_shutdown.") > addressed a comparable issue in the past regarding sk->sk_shutdown. > However, it overlooked resolving this particular data path. > This patch only offending unix_stream_sendmsg() function, since the > other reads seem to be protected by unix_state_lock() as discussed in > Link: https://lore.kernel.org/all/20240508173324.53565-1-kuniyu@amazon.com/ > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Signed-off-by: Breno Leitao Reviewed-by: Kuniyuki Iwashima Thanks! > --- > Changelog: > > v2: > * Only fix the usecase reported by KCSAN > * Targeting net instead of net-next > --- > net/unix/af_unix.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c > index dc1651541723..fa906ec5e657 100644 > --- a/net/unix/af_unix.c > +++ b/net/unix/af_unix.c > @@ -2224,7 +2224,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, > goto out_err; > } > > - if (sk->sk_shutdown & SEND_SHUTDOWN) > + if (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) > goto pipe_err; > > while (sent < len) { > -- > 2.43.0 >