From patchwork Tue Apr 26 08:21:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 566706 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 D36D4C433F5 for ; Tue, 26 Apr 2022 08:32:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345234AbiDZIfW (ORCPT ); Tue, 26 Apr 2022 04:35:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345637AbiDZIev (ORCPT ); Tue, 26 Apr 2022 04:34:51 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D4C17B106; Tue, 26 Apr 2022 01:27:58 -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 sin.source.kernel.org (Postfix) with ESMTPS id C825ACE1BB9; Tue, 26 Apr 2022 08:27:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA2D7C385A0; Tue, 26 Apr 2022 08:27:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650961675; bh=WVYkqLeGjLbMgDhS95W2RDf8W0KTKaLbtiJNQ7wweZA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2AIb2Q6O7ZpzeSJRk+3IxBpYhKbkOQ+GdiDLAkcDDtfndjNOgbM4Y07W8mBH7/e2y d1bYrOwW/M4yMfrxiuuwOWG7C2K8N96G3WjMtC6xnn9pHn2M5G3mesYiMT+OO/RR+X fgVQilZPTtgi+xAYOjy4V8MFc3y9A5z7NIVLM/Aw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Duoming Zhou , "David S. Miller" , Ovidiu Panait Subject: [PATCH 4.19 47/53] ax25: fix UAF bugs of net_device caused by rebinding operation Date: Tue, 26 Apr 2022 10:21:27 +0200 Message-Id: <20220426081737.030613677@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220426081735.651926456@linuxfoundation.org> References: <20220426081735.651926456@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 feef318c855a361a1eccd880f33e88c460eb63b4 upstream. The ax25_kill_by_device() will set s->ax25_dev = NULL and call ax25_disconnect() to change states of ax25_cb and sock, if we call ax25_bind() before ax25_kill_by_device(). However, if we call ax25_bind() again between the window of ax25_kill_by_device() and ax25_dev_device_down(), the values and states changed by ax25_kill_by_device() will be reassigned. Finally, ax25_dev_device_down() will deallocate net_device. If we dereference net_device in syscall functions such as ax25_release(), ax25_sendmsg(), ax25_getsockopt(), ax25_getname() and ax25_info_show(), a UAF bug will occur. One of the possible race conditions is shown below: (USE) | (FREE) ax25_bind() | | ax25_kill_by_device() ax25_bind() | ax25_connect() | ... | ax25_dev_device_down() | ... | dev_put_track(dev, ...) //FREE ax25_release() | ... ax25_send_control() | alloc_skb() //USE | the corresponding fail log is shown below: =============================================================== BUG: KASAN: use-after-free in ax25_send_control+0x43/0x210 ... Call Trace: ... ax25_send_control+0x43/0x210 ax25_release+0x2db/0x3b0 __sock_release+0x6d/0x120 sock_close+0xf/0x20 __fput+0x11f/0x420 ... Allocated by task 1283: ... __kasan_kmalloc+0x81/0xa0 alloc_netdev_mqs+0x5a/0x680 mkiss_open+0x6c/0x380 tty_ldisc_open+0x55/0x90 ... Freed by task 1969: ... kfree+0xa3/0x2c0 device_release+0x54/0xe0 kobject_put+0xa5/0x120 tty_ldisc_kill+0x3e/0x80 ... In order to fix these UAF bugs caused by rebinding operation, this patch adds dev_hold_track() into ax25_bind() and corresponding dev_put_track() into ax25_kill_by_device(). Signed-off-by: Duoming Zhou Signed-off-by: David S. Miller [OP: backport to 4.19: adjust dev_put_track()->dev_put() and dev_hold_track()->dev_hold()] Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- net/ax25/af_ax25.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -101,6 +101,7 @@ again: spin_unlock_bh(&ax25_list_lock); lock_sock(sk); s->ax25_dev = NULL; + dev_put(ax25_dev->dev); ax25_dev_put(ax25_dev); release_sock(sk); ax25_disconnect(s, ENETUNREACH); @@ -1125,8 +1126,10 @@ static int ax25_bind(struct socket *sock } } - if (ax25_dev != NULL) + if (ax25_dev) { ax25_fillin_cb(ax25, ax25_dev); + dev_hold(ax25_dev->dev); + } done: ax25_cb_add(ax25);