From patchwork Tue Apr 26 08:21:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 568013 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B77C1C433F5 for ; Tue, 26 Apr 2022 08:32:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344011AbiDZIff (ORCPT ); Tue, 26 Apr 2022 04:35:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344907AbiDZIdR (ORCPT ); Tue, 26 Apr 2022 04:33:17 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5507A3D4B2; Tue, 26 Apr 2022 01:25:33 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 10C57B81CF9; Tue, 26 Apr 2022 08:25:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B3B2C385A4; Tue, 26 Apr 2022 08:25:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650961530; bh=M1EoUdOlEfwEvT3mFKB1QFhizqGdGGZuqIkH2iI4Muc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jyDGzPV/XzFpglXnXyrckCSnaU1ZHTdY+YTEpM6tpeUNFYoOAr7cDCAY3pvvL9NXu fsKtUwGMZxseQzybC14yf7tLP5NwmIblWurOpsCK9EaNESuGHmi0FGYZ9tSqMkXZN3 IB0w7rEO2W7gOM48tfwMLsm2qCVWcHlVA6UNgJ+8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Duoming Zhou , Paolo Abeni , Ovidiu Panait Subject: [PATCH 4.14 42/43] ax25: Fix UAF bugs in ax25 timers Date: Tue, 26 Apr 2022 10:21:24 +0200 Message-Id: <20220426081735.761411609@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220426081734.509314186@linuxfoundation.org> References: <20220426081734.509314186@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Duoming Zhou commit 82e31755e55fbcea6a9dfaae5fe4860ade17cbc0 upstream. There are race conditions that may lead to UAF bugs in ax25_heartbeat_expiry(), ax25_t1timer_expiry(), ax25_t2timer_expiry(), ax25_t3timer_expiry() and ax25_idletimer_expiry(), when we call ax25_release() to deallocate ax25_dev. One of the UAF bugs caused by ax25_release() is shown below: (Thread 1) | (Thread 2) ax25_dev_device_up() //(1) | ... | ax25_kill_by_device() ax25_bind() //(2) | ax25_connect() | ... ax25_std_establish_data_link() | ax25_start_t1timer() | ax25_dev_device_down() //(3) mod_timer(&ax25->t1timer,..) | | ax25_release() (wait a time) | ... | ax25_dev_put(ax25_dev) //(4)FREE ax25_t1timer_expiry() | ax25->ax25_dev->values[..] //USE| ... ... | We increase the refcount of ax25_dev in position (1) and (2), and decrease the refcount of ax25_dev in position (3) and (4). The ax25_dev will be freed in position (4) and be used in ax25_t1timer_expiry(). The fail log is shown below: ============================================================== [ 106.116942] BUG: KASAN: use-after-free in ax25_t1timer_expiry+0x1c/0x60 [ 106.116942] Read of size 8 at addr ffff88800bda9028 by task swapper/0/0 [ 106.116942] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.17.0-06123-g0905eec574 [ 106.116942] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-14 [ 106.116942] Call Trace: ... [ 106.116942] ax25_t1timer_expiry+0x1c/0x60 [ 106.116942] call_timer_fn+0x122/0x3d0 [ 106.116942] __run_timers.part.0+0x3f6/0x520 [ 106.116942] run_timer_softirq+0x4f/0xb0 [ 106.116942] __do_softirq+0x1c2/0x651 ... This patch adds del_timer_sync() in ax25_release(), which could ensure that all timers stop before we deallocate ax25_dev. Signed-off-by: Duoming Zhou Signed-off-by: Paolo Abeni [OP: backport to 4.14: adjust context] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- net/ax25/af_ax25.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -1056,6 +1056,11 @@ static int ax25_release(struct socket *s ax25_destroy_socket(ax25); } if (ax25_dev) { + del_timer_sync(&ax25->timer); + del_timer_sync(&ax25->t1timer); + del_timer_sync(&ax25->t2timer); + del_timer_sync(&ax25->t3timer); + del_timer_sync(&ax25->idletimer); dev_put(ax25_dev->dev); ax25_dev_put(ax25_dev); }