From patchwork Thu Nov 24 17:51:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shigeru Yoshida X-Patchwork-Id: 13055250 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 35AD1C433FE for ; Thu, 24 Nov 2022 17:53:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229869AbiKXRxM (ORCPT ); Thu, 24 Nov 2022 12:53:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229865AbiKXRwt (ORCPT ); Thu, 24 Nov 2022 12:52:49 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D5EB109599 for ; Thu, 24 Nov 2022 09:51:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1669312312; 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=fSdsuSrgjDopfALOvm1rrQFXbKKGllyvaK04VepISNM=; b=ROZhYJSnMBkW7V74pFqn0WJV7L9KGyDe5wMJ2rwgPLq3obJDQKZHMQkEXL3GIYM3eyl8Xl fDqPFEs7poIT1o0Ix44Nw08To1A4xu58VjQQ5TZ//9bQWtGDmnZLjBHmTMTjMKb0OvquHk vZwuAvEmG5GxKPeYY4mVQ4tBMgKfyJc= Received: from mail-pj1-f69.google.com (mail-pj1-f69.google.com [209.85.216.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-422-fWR4Wk77M6OhsPKpPyEpTA-1; Thu, 24 Nov 2022 12:51:50 -0500 X-MC-Unique: fWR4Wk77M6OhsPKpPyEpTA-1 Received: by mail-pj1-f69.google.com with SMTP id x8-20020a17090a6b4800b00218ae9b2a47so1425553pjl.6 for ; Thu, 24 Nov 2022 09:51:50 -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=fSdsuSrgjDopfALOvm1rrQFXbKKGllyvaK04VepISNM=; b=c+B2Ug+VYBicaJbJyvWUEDMYT7IQODgNMEGgq4zL/5nWh9P3ILXcAqFT/4jd818zmj E8H2oqY0Qn/+NUHUPIt4OLL5vtjcaVStz/DtyqrB2D3hLGByAFnMbDl7jGdG7cZ2JRek EanlyhhacNXp7/mlZfQU12Iaj6Hz0KqTxGcP9sPvu9gDJLedTMjezqV7ZsXzYXUh/E16 G81Rao+okU0rsMkP0Lvo/+OT6ChOgo1zIgGo0CVBib9BqTz+LkOuQ7faI4POAM2YMpMK fOR/g/wmjOx740bI/kW4rLjcWiy5dXbJ87bk7twMcsooRAahNR1bHuDXpQqZfq4LZr6M avyA== X-Gm-Message-State: ANoB5pm/BjiNT8WwSDRC/SbrfjBotemOwA0yA4EbvCOTBXiEVozIRvXu ECEtDPIje8idPTHCfcbRnnTcyZZL1aqXSFw1SmaYx2G67y2iz/dLDcvUzvW82YwVBiJs3J7/VK3 N9Z6LSpr04OYeFk+q X-Received: by 2002:a17:902:ce0e:b0:172:86a2:8e68 with SMTP id k14-20020a170902ce0e00b0017286a28e68mr15973645plg.27.1669312309285; Thu, 24 Nov 2022 09:51:49 -0800 (PST) X-Google-Smtp-Source: AA0mqf7QJlepYjWsZ1z1GX6KIUy8Kfes+LstjyEEIEoRwJESdyt5NKcP15Q7qZbt8DdJt0ShoBwspw== X-Received: by 2002:a17:902:ce0e:b0:172:86a2:8e68 with SMTP id k14-20020a170902ce0e00b0017286a28e68mr15973615plg.27.1669312308591; Thu, 24 Nov 2022 09:51:48 -0800 (PST) Received: from ryzen.. ([240d:1a:c0d:9f00:fc9c:8ee9:e32c:2d9]) by smtp.gmail.com with ESMTPSA id y75-20020a62644e000000b0056ee49d6e95sm1484968pfb.86.2022.11.24.09.51.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Nov 2022 09:51:48 -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, jasowang@redhat.com, Shigeru Yoshida , syzbot+106f9b687cd64ee70cd1@syzkaller.appspotmail.com Subject: [PATCH v3] net: tun: Fix use-after-free in tun_detach() Date: Fri, 25 Nov 2022 02:51:34 +0900 Message-Id: <20221124175134.1589053-1-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 --- v3: - Remove redundant synchronize_rcu() 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 | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 7a3ab3427369..24001112c323 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 +701,9 @@ 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)