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 B8D6BC4332F for ; Tue, 28 Dec 2021 10:42:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236263AbhL1KmE (ORCPT ); Tue, 28 Dec 2021 05:42:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236221AbhL1KmD (ORCPT ); Tue, 28 Dec 2021 05:42:03 -0500 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F34EBC06173F for ; Tue, 28 Dec 2021 02:42:02 -0800 (PST) Received: by mail-pl1-x62a.google.com with SMTP id u16so13279219plg.9 for ; Tue, 28 Dec 2021 02:42:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=V2lufGQJcmKY2cAym2JF7ioLQmysawSKTxtO0HzaVFI=; b=4VJdUsBEhq7t1WkLu0/FX++pPUrIZ+ihdvsBbFfX+mmt2GHAAxjUBUgZc7g/AbJbrO wU4vxR9KaynziVK8dMTNAXhQJCw6Elg3qWdUZ5K/PUJSzUjIvCOvpH3/LnmySt3kkTmh NA7s02zDHtbzwn9ByceoHkoZs48u5D420IcJ77O/IfnHryIqQuA8AU4I5Ux0rajkAmO/ eMHVeKwiUs2eOPAdvZUoXrPbxEDWc1le9KRcJJQKyD589oCCVXnN1BB5ohc1mtZawffC 24ALejde0dNyj7Ri1eyKqknxFzrHVwKc2aw7ZYT15a0byY01evzW+8dwIiJ+k8uVyO+L swdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=V2lufGQJcmKY2cAym2JF7ioLQmysawSKTxtO0HzaVFI=; b=NWsTuWQFJsO5g66OSFUE4HNTMRcGpig/kmt/5sLER2qZCwIiPdeDzPFeuDUi+IHmPW G/gc/9853/fEBdb4uwD64pEXjxsyRRH/4eVN5z0dRZv4jzCTsj4ymHYjBHe0pZVcTLse wXRc8KbBftRQdguqk1Kxu8UQZMoMSwgoIAMtgQF6EqmtBUp4xlJIc2m4eRBdmSlRoH6z 3WvQ1kmo0pWDzPVPsewddotimA78xDBvw6YMUP6i/I32Q/qleFWRh2X8hIC9K08QrcwH kXCJxT0D9vIvwGWOgRBJLtPz2VVve9cetqnaernKdRErbNEvRqw6Th+t0yxaURCrDvC/ BtBw== X-Gm-Message-State: AOAM53370uk9hhRTWmOgBSkHehSxLESad01c7y5UR15ablaXgcULh+nF wFx9ctvOSUzHaIp7rnnQ3PzRQA== X-Google-Smtp-Source: ABdhPJyZpAuRWD66Y8AJSmTUZaoWU1FmBaH3I+KVTM+T0G2Gl26osron+9O84L86g+zngcUGbKodXQ== X-Received: by 2002:a17:90a:c788:: with SMTP id gn8mr25637549pjb.212.1640688122515; Tue, 28 Dec 2021 02:42:02 -0800 (PST) Received: from C02FF4E5ML7H.bytedance.net ([153.254.110.101]) by smtp.gmail.com with ESMTPSA id g16sm17521397pfv.159.2021.12.28.02.41.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Dec 2021 02:42:02 -0800 (PST) From: Muchun Song To: davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, kuba@kernel.org, xemul@openvz.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Muchun Song , Cong Wang , Fam Zheng , stable@vger.kernel.org Subject: [PATCH] net: fix use-after-free in tw_timer_handler Date: Tue, 28 Dec 2021 18:41:45 +0800 Message-Id: <20211228104145.9426-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.30.1 (Apple Git-130) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A real world panic issue was found as follow in Linux 5.4. BUG: unable to handle page fault for address: ffffde49a863de28 PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0 RIP: 0010:tw_timer_handler+0x20/0x40 Call Trace: call_timer_fn+0x2b/0x120 run_timer_softirq+0x1ef/0x450 __do_softirq+0x10d/0x2b8 irq_exit+0xc7/0xd0 smp_apic_timer_interrupt+0x68/0x120 apic_timer_interrupt+0xf/0x20 This issue was also reported since 2017 in the thread [1], unfortunately, the issue was still can be reproduced after fixing DCCP. The ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net namespace is destroyed since tcp_sk_ops is registered befrore ipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops in the list of pernet_list. There will be a use-after-free on net->mib.net_statistics in tw_timer_handler after ipv4_mib_exit_net if there are some inflight time-wait timers. This bug is not introduced by commit f2bf415cfed7 ("mib: add net to NET_ADD_STATS_BH") since the net_statistics is a global variable instead of dynamic allocation and freeing. Actually, commit 61a7e26028b9 ("mib: put net statistics on struct net") introduces the bug since it put net statistics on struct net and free it when net namespace is destroyed. Moving init_ipv4_mibs() to the front of tcp_init() to fix this bug and replace pr_crit() with panic() since continuing is meaningless when init_ipv4_mibs() fails. [1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1 Fixes: 61a7e26028b9 ("mib: put net statistics on struct net") Signed-off-by: Muchun Song Cc: Xiongchun Duan Cc: Cong Wang Cc: Fam Zheng Cc: --- net/ipv4/af_inet.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 04067b249bf3..cb8ba7a0a114 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1985,6 +1985,10 @@ static int __init inet_init(void) ip_init(); + /* Initialise per-cpu ipv4 mibs */ + if (init_ipv4_mibs()) + panic("%s: Cannot init ipv4 mibs\n", __func__); + /* Setup TCP slab cache for open requests. */ tcp_init(); @@ -2015,12 +2019,6 @@ static int __init inet_init(void) if (init_inet_pernet_ops()) pr_crit("%s: Cannot init ipv4 inet pernet ops\n", __func__); - /* - * Initialise per-cpu ipv4 mibs - */ - - if (init_ipv4_mibs()) - pr_crit("%s: Cannot init ipv4 mibs\n", __func__); ipv4_proc_init(); -- 2.11.0