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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39476C4332F for ; Mon, 5 Dec 2022 19:38:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234301AbiLETio (ORCPT ); Mon, 5 Dec 2022 14:38:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234453AbiLETiY (ORCPT ); Mon, 5 Dec 2022 14:38:24 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEE2D29CAA for ; Mon, 5 Dec 2022 11:35:20 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 2780861307 for ; Mon, 5 Dec 2022 19:35:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36D56C433D6; Mon, 5 Dec 2022 19:35:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670268919; bh=WfymIi/l/K11D/YFO0RbUiHW1d9I+QF0Gmcvgv5cphg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WJV1oZs4klVTSHWT0cK4CXr366ggqB4sQ/z0zYmZ3NI15nQEP1FwQ1Kyqcn17Fllc zvC8wtZs+I93QRVOSkH7lURiwYyXT0/p2B64h2LOtko64TQ4I+wAHnkOW9d73GcG6U lU/5ZCQW3+V4MNlKqH/z+eZCNtVfRnipbiPTG5R0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+106f9b687cd64ee70cd1@syzkaller.appspotmail.com, Shigeru Yoshida , Paolo Abeni , Sasha Levin Subject: [PATCH 5.15 060/120] net: tun: Fix use-after-free in tun_detach() Date: Mon, 5 Dec 2022 20:10:00 +0100 Message-Id: <20221205190808.424344272@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221205190806.528972574@linuxfoundation.org> References: <20221205190806.528972574@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Shigeru Yoshida [ Upstream commit 5daadc86f27ea4d691e2131c04310d0418c6cd12 ] syzbot reported use-after-free in tun_detach() [1]. This causes call trace like below: ================================================================== BUG: KASAN: use-after-free in notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75 Read of size 8 at addr ffff88807324e2a8 by task syz-executor.0/3673 CPU: 0 PID: 3673 Comm: syz-executor.0 Not tainted 6.1.0-rc5-syzkaller-00044-gcc675d22e422 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x15e/0x461 mm/kasan/report.c:395 kasan_report+0xbf/0x1f0 mm/kasan/report.c:495 notifier_call_chain+0x1ee/0x200 kernel/notifier.c:75 call_netdevice_notifiers_info+0x86/0x130 net/core/dev.c:1942 call_netdevice_notifiers_extack net/core/dev.c:1983 [inline] call_netdevice_notifiers net/core/dev.c:1997 [inline] netdev_wait_allrefs_any net/core/dev.c:10237 [inline] netdev_run_todo+0xbc6/0x1100 net/core/dev.c:10351 tun_detach drivers/net/tun.c:704 [inline] tun_chr_close+0xe4/0x190 drivers/net/tun.c:3467 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xb3d/0x2a30 kernel/exit.c:820 do_group_exit+0xd4/0x2a0 kernel/exit.c:950 get_signal+0x21b1/0x2440 kernel/signal.c:2858 arch_do_signal_or_restart+0x86/0x2300 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296 do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd The cause of the issue is that sock_put() from __tun_detach() drops last reference count for struct net, and then notifier_call_chain() from netdev_state_change() accesses that struct net. This patch fixes the issue by calling sock_put() from tun_detach() after all necessary accesses for the struct net has done. Fixes: 83c1f36f9880 ("tun: send netlink notification when the device is modified") Reported-by: syzbot+106f9b687cd64ee70cd1@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=96eb7f1ce75ef933697f24eeab928c4a716edefe [1] Signed-off-by: Shigeru Yoshida Link: https://lore.kernel.org/r/20221124175134.1589053-1-syoshida@redhat.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- drivers/net/tun.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 575077998d8a..a1dda57c812d 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -687,7 +687,6 @@ static void __tun_detach(struct tun_file *tfile, bool clean) if (tun) xdp_rxq_info_unreg(&tfile->xdp_rxq); ptr_ring_cleanup(&tfile->tx_ring, tun_ptr_free); - sock_put(&tfile->sk); } } @@ -703,6 +702,9 @@ static void tun_detach(struct tun_file *tfile, bool clean) if (dev) netdev_state_change(dev); rtnl_unlock(); + + if (clean) + sock_put(&tfile->sk); } static void tun_detach_all(struct net_device *dev) -- 2.35.1