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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 ED643C433E1 for ; Mon, 17 Aug 2020 19:20:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD3DB204EC for ; Mon, 17 Aug 2020 19:20:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597692035; bh=/omsBwg8Yyncdrw92Temo+2BdmMOicqXhOUwneH6NX0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=P6q8dhxURS0aiOuJruvcqpk8ria61nRCdTF7WtoTt87ighvzpXoMsJYZbrcm2Kw5W DPl6gwSBwk35I4FxCwuPpAzoYFLRLUKJbeYFs/OQPNU1yt3yqv2uSfELpsuyTnt83c cytRyeNMYqglfey+WHBNo4KDxlOwjhdUGxtfXlYs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392316AbgHQTUZ (ORCPT ); Mon, 17 Aug 2020 15:20:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:44338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730517AbgHQPgu (ORCPT ); Mon, 17 Aug 2020 11:36:50 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C7DC32310F; Mon, 17 Aug 2020 15:36:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597678609; bh=/omsBwg8Yyncdrw92Temo+2BdmMOicqXhOUwneH6NX0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ykN/sySLLZISY9YpjYMmxlU7V6ak5oMxO+LvzOUvTwRqSo9CUfL7QteL7SbZDJitx SqSXI60uojad3G/Ss+IoqtAxQumDjvSmm0pMe8pkzadQ6t44UbtOOTVzNjLqesB+sj /aBhOiiXFpPl44r6u7OWiivkGkGFQNT319QRo1vs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefano Garzarella , Jorgen Hansen , "David S. Miller" , syzbot+a61bac2fcc1a7c6623fe@syzkaller.appspotmail.com Subject: [PATCH 5.8 394/464] vsock: fix potential null pointer dereference in vsock_poll() Date: Mon, 17 Aug 2020 17:15:47 +0200 Message-Id: <20200817143852.652250005@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143833.737102804@linuxfoundation.org> References: <20200817143833.737102804@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stefano Garzarella [ Upstream commit 1980c05844830a44708c98c96d600833aa3fae08 ] syzbot reported this issue where in the vsock_poll() we find the socket state at TCP_ESTABLISHED, but 'transport' is null: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097] CPU: 0 PID: 8227 Comm: syz-executor.2 Not tainted 5.8.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:vsock_poll+0x75a/0x8e0 net/vmw_vsock/af_vsock.c:1038 Call Trace: sock_poll+0x159/0x460 net/socket.c:1266 vfs_poll include/linux/poll.h:90 [inline] do_pollfd fs/select.c:869 [inline] do_poll fs/select.c:917 [inline] do_sys_poll+0x607/0xd40 fs/select.c:1011 __do_sys_poll fs/select.c:1069 [inline] __se_sys_poll fs/select.c:1057 [inline] __x64_sys_poll+0x18c/0x440 fs/select.c:1057 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384 entry_SYSCALL_64_after_hwframe+0x44/0xa9 This issue can happen if the TCP_ESTABLISHED state is set after we read the vsk->transport in the vsock_poll(). We could put barriers to synchronize, but this can only happen during connection setup, so we can simply check that 'transport' is valid. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Reported-and-tested-by: syzbot+a61bac2fcc1a7c6623fe@syzkaller.appspotmail.com Signed-off-by: Stefano Garzarella Reviewed-by: Jorgen Hansen Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/vmw_vsock/af_vsock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -1032,7 +1032,7 @@ static __poll_t vsock_poll(struct file * } /* Connected sockets that can produce data can be written. */ - if (sk->sk_state == TCP_ESTABLISHED) { + if (transport && sk->sk_state == TCP_ESTABLISHED) { if (!(sk->sk_shutdown & SEND_SHUTDOWN)) { bool space_avail_now = false; int ret = transport->notify_poll_out(