From patchwork Sun Nov 20 09:02:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shigeru Yoshida X-Patchwork-Id: 13049931 X-Patchwork-Delegate: kuba@kernel.org 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 B3800C4332F for ; Sun, 20 Nov 2022 09:03:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229505AbiKTJDb (ORCPT ); Sun, 20 Nov 2022 04:03:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229480AbiKTJDb (ORCPT ); Sun, 20 Nov 2022 04:03:31 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89B1510B8 for ; Sun, 20 Nov 2022 01:02:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668934952; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=oEYRj+tvOCAOAYfObhytG1SVOeN3XgfIQzsjLTeBgGY=; b=b/yM8opZEW1JjuO7UTNj7NlVg192MAqzjUVZ4MdgyoG9SiBaGgIzv9UhxzMU6YBEN7siQ8 bWIaGgMxpGZr03gS2KQFiDZAK2/I1FCFSt3PTGhklh5JricLar1UjdkjaTMQqli43sygY0 J4+HhIALZm398fuDi08beOYEmqG98AM= Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-351-Mgmf45zPNDi5i8IY6rorIA-1; Sun, 20 Nov 2022 04:02:31 -0500 X-MC-Unique: Mgmf45zPNDi5i8IY6rorIA-1 Received: by mail-pl1-f200.google.com with SMTP id p18-20020a170902a41200b00188e87d0f04so7155737plq.14 for ; Sun, 20 Nov 2022 01:02:31 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=oEYRj+tvOCAOAYfObhytG1SVOeN3XgfIQzsjLTeBgGY=; b=0JmO3VslBPGwsa7wL5EP9efVzQY9VXilghHCp8JVnP4+JFltPySyOMOsF/4rVzm00d XbgDfs5ZPzno58fziV136gp0TJT9bLdQUA18bje54IQbHf568EFIOmZ0VRgEgDDFA4UD /+Vq7gpAIeJJsVXMQJIJ20TfIXoh9oZH6OjknJyxQIRtrh9kUONqUv+AqrHIAaBC6kTz R3l87P54ebGKEHFUCvs+3gAay1x0DsfQn4fFszuYCMI8m2sJPw5n/WeiV51JUGcIunOE 8FElAhitrQ/v4oDBZ0Ue5KroBUsdvhtPxQoUFroA5FOTiuav3JLmWBblj3Rvu6KdTdwL iL+Q== X-Gm-Message-State: ANoB5pkKZmJaJwD/iwzkYWwzgLnasgTcBD436C3yf0oe1MjxOaBoS7hy kOEgBxHrztGmG3sA/yMhAISg34y2i4pUxcA8sg6fAIp0tc18PHFtLoLVkXwZR2bGtJs3myqL6gH W6AtHDVmwUELhmNxp X-Received: by 2002:a17:902:b40b:b0:188:ca57:ce0c with SMTP id x11-20020a170902b40b00b00188ca57ce0cmr7033109plr.57.1668934949248; Sun, 20 Nov 2022 01:02:29 -0800 (PST) X-Google-Smtp-Source: AA0mqf4c5i9VsfKVT/Mxkk5lyuy7Yin/M7or7UVp/BJAMTxyKaeZuWn4RbXKkx9F9pBOVxYbPS6Ptg== X-Received: by 2002:a17:902:b40b:b0:188:ca57:ce0c with SMTP id x11-20020a170902b40b00b00188ca57ce0cmr7033078plr.57.1668934948810; Sun, 20 Nov 2022 01:02:28 -0800 (PST) Received: from ryzen.. ([240d:1a:c0d:9f00:fc9c:8ee9:e32c:2d9]) by smtp.gmail.com with ESMTPSA id h129-20020a625387000000b0056c063dd4cfsm6323422pfb.66.2022.11.20.01.02.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Nov 2022 01:02:28 -0800 (PST) From: Shigeru Yoshida To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Shigeru Yoshida , syzbot+106f9b687cd64ee70cd1@syzkaller.appspotmail.com Subject: [PATCH v2] net: tun: Fix use-after-free in tun_detach() Date: Sun, 20 Nov 2022 18:02:13 +0900 Message-Id: <20221120090213.922567-1-syoshida@redhat.com> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org 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 --- v2: - Include symbolic stack trace - Add Fixes and Reported-by tags v1: https://lore.kernel.org/all/20221119075615.723290-1-syoshida@redhat.com/ --- drivers/net/tun.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 7a3ab3427369..ce9fcf4c8ef4 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -686,7 +686,6 @@ 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); } } @@ -702,6 +701,11 @@ static void tun_detach(struct tun_file *tfile, bool clean) if (dev) netdev_state_change(dev); rtnl_unlock(); + + if (clean) { + synchronize_rcu(); + sock_put(&tfile->sk); + } } static void tun_detach_all(struct net_device *dev)