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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DDE4C43219 for ; Thu, 2 May 2019 15:13:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02DCB20675 for ; Thu, 2 May 2019 15:13:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726449AbfEBPNX (ORCPT ); Thu, 2 May 2019 11:13:23 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:41638 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726268AbfEBPNW (ORCPT ); Thu, 2 May 2019 11:13:22 -0400 Received: by mail-wr1-f68.google.com with SMTP id c12so3883897wrt.8 for ; Thu, 02 May 2019 08:13:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=3pLbw6omsWuPgSQnYCfN0GtkX9q9KvEVqwsUzq+USwk=; b=m7ffLxVVMIWFWbyUledvFUxzr2ACg7jD5fi3xbWcVgSPuGbht0dgYN/T4OncButPh9 1eXz3BzJc4rfuo9PRknue9oXaZbyMHz4zu0Et+whSWivv9He+qT8XtXifGG4gX3BfZnA V64AmC5NrnApboJ7Ah/vvnDOtb3mQq36BE2ZIozDHPoDHSR6Xq58XYSz4cgJQvtCWZ32 D4moBWf6Hm37d1E3Kz41AZZ19rW0yoZ/Kxjg8EWdDEukNofJq2P0e0UQkIB0Qz8w5FL0 Da+/54ogMp7Rou6L9Om+uezT/zE/GPnh3a0srkgDuKCU1+WfD0RD6CS8a3xn67mHfrCB a3NQ== X-Gm-Message-State: APjAAAVtoIm7v/hZc9jZ/Q6Qp3CcdxT/Alr9ajVp9jrxb/c8FQODi3GA TPYf00g7sUTGdQ86LD2XejEQNQ== X-Google-Smtp-Source: APXvYqwcDElKSu7Ll3TBTrQeIHFS+taBb8h9T8Er1GBYOMMnHim4Ip2e7PhnRkQqvRYX1CkcHdeQfw== X-Received: by 2002:adf:b696:: with SMTP id j22mr3233428wre.85.1556810000810; Thu, 02 May 2019 08:13:20 -0700 (PDT) Received: from mcroce-redhat.mxp.redhat.com (nat-pool-mxp-t.redhat.com. [149.6.153.186]) by smtp.gmail.com with ESMTPSA id 195sm3166760wme.32.2019.05.02.08.13.19 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 02 May 2019 08:13:19 -0700 (PDT) From: Matteo Croce To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jamal Hadi Salim , Cong Wang , Jiri Pirko , "David S. Miller" , Vlad Buslov Subject: [PATCH net] cls_cgroup: avoid panic when receiving a packet before filter set Date: Thu, 2 May 2019 17:13:18 +0200 Message-Id: <20190502151318.1884-1-mcroce@redhat.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a cgroup classifier is added, there is a small time interval in which tp->root is NULL. If we receive a packet in this small time slice a NULL pointer dereference will happen, leading to a kernel panic: # mkdir /sys/fs/cgroup/net_cls/0 # echo 0x100001 > /sys/fs/cgroup/net_cls/0/net_cls.classid # echo $$ >/sys/fs/cgroup/net_cls/0/tasks # ping -qfb 255.255.255.255 -I eth0 &>/dev/null & # tc qdisc add dev eth0 root handle 10: htb # while : ; do > tc filter add dev eth0 parent 10: protocol ip prio 10 handle 1: cgroup > tc filter delete dev eth0 > done Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028 Mem abort info: ESR = 0x96000005 Exception class = DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000005 CM = 0, WnR = 0 user pgtable: 4k pages, 39-bit VAs, pgdp = 0000000098a7ff91 [0000000000000028] pgd=0000000000000000, pud=0000000000000000 Internal error: Oops: 96000005 [#1] SMP Modules linked in: sch_htb cls_cgroup algif_hash af_alg nls_iso8859_1 nls_cp437 vfat fat xhci_plat_hcd m25p80 spi_nor xhci_hcd mtd usbcore usb_common spi_orion sfp i2c_mv64xxx phy_generic mdio_i2c marvell10g i2c_core mvpp2 mvmdio phylink sbsa_gwdt ip_tables x_tables autofs4 Process ping (pid: 5421, stack limit = 0x00000000b20b1505) CPU: 3 PID: 5421 Comm: ping Not tainted 5.1.0-rc6 #31 Hardware name: Marvell 8040 MACCHIATOBin Double-shot (DT) pstate: 60000005 (nZCv daif -PAN -UAO) pc : cls_cgroup_classify+0x80/0xec [cls_cgroup] lr : cls_cgroup_classify+0x34/0xec [cls_cgroup] sp : ffffff8012e6b850 x29: ffffff8012e6b850 x28: ffffffc423dd3c00 x27: ffffff801093ebc0 x26: ffffffc425a85b00 x25: 0000000020000000 x24: 0000000000000000 x23: ffffff8012e6b910 x22: ffffffc428db4900 x21: ffffff8012e6b910 x20: 0000000000100001 x19: 0000000000000000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 000000000000001c x11: 0000000000000018 x10: ffffff8012e6b840 x9 : 0000000000003580 x8 : 000000000000009d x7 : 0000000000000002 x6 : ffffff8012e6b860 x5 : 000000007cd66ffe x4 : 000000009742a193 x3 : ffffff800865b4d8 x2 : ffffff8012e6b910 x1 : 0000000000000400 x0 : ffffffc42c38f300 Call trace: cls_cgroup_classify+0x80/0xec [cls_cgroup] tcf_classify+0x78/0x138 htb_enqueue+0x74/0x320 [sch_htb] __dev_queue_xmit+0x3e4/0x9d0 dev_queue_xmit+0x24/0x30 ip_finish_output2+0x2e4/0x4d0 ip_finish_output+0x1d8/0x270 ip_mc_output+0xa8/0x240 ip_local_out+0x58/0x68 ip_send_skb+0x2c/0x88 ip_push_pending_frames+0x44/0x50 raw_sendmsg+0x458/0x830 inet_sendmsg+0x54/0xe8 sock_sendmsg+0x34/0x50 __sys_sendto+0xd0/0x120 __arm64_sys_sendto+0x30/0x40 el0_svc_common.constprop.0+0x88/0xf8 el0_svc_handler+0x2c/0x38 el0_svc+0x8/0xc Code: 39496001 360002a1 b9425c14 34000274 (79405260) Suggested-by: Cong Wang Fixes: ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") Signed-off-by: Matteo Croce --- net/sched/cls_cgroup.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c index 4c1567854f95..706a160142ea 100644 --- a/net/sched/cls_cgroup.c +++ b/net/sched/cls_cgroup.c @@ -32,6 +32,8 @@ static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct cls_cgroup_head *head = rcu_dereference_bh(tp->root); u32 classid = task_get_classid(skb); + if (unlikely(!head)) + return -1; if (!classid) return -1; if (!tcf_em_tree_match(skb, &head->ematches, NULL)) -- 2.21.0