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=-10.0 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 52F39C433DF for ; Mon, 3 Aug 2020 12:33:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27DDC2076B for ; Mon, 3 Aug 2020 12:33:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596458000; bh=UBRBwNUBAkcMQm7k4AI2Gc1Fdp/NT7POSOWwfxAQqok=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=SOtAgn4S3b4ndNBAdujJ+ZGipcyFiVl3sL8fFF3idJ/n6WlWdVkpUgdrbFfWXFHp6 UVo6xhf+UfuUtCAsrgna2E231QmfC4I/anS8LkS9VhdpZan5mRTNH58jF94cE4a30E rXSc0WH5ncMWFy89F4v86Ol6CUhveAzKPer4XDSI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729415AbgHCMdT (ORCPT ); Mon, 3 Aug 2020 08:33:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:33062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729401AbgHCMdO (ORCPT ); Mon, 3 Aug 2020 08:33:14 -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 2B9A6204EC; Mon, 3 Aug 2020 12:33:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457992; bh=UBRBwNUBAkcMQm7k4AI2Gc1Fdp/NT7POSOWwfxAQqok=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P8ZcQXjxGpVBoFCjiGGS01JqdaUb0oRJkSAi4+CIUFOoxeRY+qT0vb2brlMoOA76i 2oRdPQ+5Lj+OAJyxvkUlvNiAm/SoJuCbFKm12Kh3a8GqPNLPSm20SQV9HfZwjCYxbX rWq7iGIueJ2Bto3esVG2edTI1yyeHlkJ47mZKCZg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+6db548b615e5aeefdce2@syzkaller.appspotmail.com, YueHaibing , "David S. Miller" Subject: [PATCH 4.19 26/56] net/x25: Fix null-ptr-deref in x25_disconnect Date: Mon, 3 Aug 2020 14:19:41 +0200 Message-Id: <20200803121851.621479441@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200803121850.306734207@linuxfoundation.org> References: <20200803121850.306734207@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: YueHaibing commit 8999dc89497ab1c80d0718828e838c7cd5f6bffe upstream. We should check null before do x25_neigh_put in x25_disconnect, otherwise may cause null-ptr-deref like this: #include #include int main() { int sck_x25; sck_x25 = socket(AF_X25, SOCK_SEQPACKET, 0); close(sck_x25); return 0; } BUG: kernel NULL pointer dereference, address: 00000000000000d8 CPU: 0 PID: 4817 Comm: t2 Not tainted 5.7.0-rc3+ #159 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3- RIP: 0010:x25_disconnect+0x91/0xe0 Call Trace: x25_release+0x18a/0x1b0 __sock_release+0x3d/0xc0 sock_close+0x13/0x20 __fput+0x107/0x270 ____fput+0x9/0x10 task_work_run+0x6d/0xb0 exit_to_usermode_loop+0x102/0x110 do_syscall_64+0x23c/0x260 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Reported-by: syzbot+6db548b615e5aeefdce2@syzkaller.appspotmail.com Fixes: 4becb7ee5b3d ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect") Signed-off-by: YueHaibing Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/x25/x25_subr.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/net/x25/x25_subr.c +++ b/net/x25/x25_subr.c @@ -362,10 +362,12 @@ void x25_disconnect(struct sock *sk, int sk->sk_state_change(sk); sock_set_flag(sk, SOCK_DEAD); } - read_lock_bh(&x25_list_lock); - x25_neigh_put(x25->neighbour); - x25->neighbour = NULL; - read_unlock_bh(&x25_list_lock); + if (x25->neighbour) { + read_lock_bh(&x25_list_lock); + x25_neigh_put(x25->neighbour); + x25->neighbour = NULL; + read_unlock_bh(&x25_list_lock); + } } /*