From patchwork Mon Apr 29 17:38:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matteo Croce X-Patchwork-Id: 1092760 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44tBhZ1Yflz9sML for ; Tue, 30 Apr 2019 03:38:22 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729125AbfD2RiV (ORCPT ); Mon, 29 Apr 2019 13:38:21 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:33057 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728844AbfD2RiK (ORCPT ); Mon, 29 Apr 2019 13:38:10 -0400 Received: by mail-wr1-f67.google.com with SMTP id s18so17344427wrp.0 for ; Mon, 29 Apr 2019 10:38:08 -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=0omHDewSx32O4bBDBWpepZGBksu0q9LlHFraC8bW9WE=; b=asDaD9AxKe1nQCBDnfGBguX2l9g6ulARQXYBsTfh7EsEFHA0MAJocRADtBwDuh0HA6 vEWZ/RfmhbRo31BApfgB84jLjx2dEWwbTj8ZXYe6m7HZ+rxrAuKLREMdXe8DSt2UVpZL 4r9qCCtrhJnONQEjl22HDCTu85e04am1C9mNLTREkSOLnwVNsdtjf+9Nw4Z56RYRh8Y7 2DmJTsq2hm8jr6Byc9LkMjVLhU7LZj0dQPJZOwgwJUoFS5P4iWde+b6Qd7wR4jeRfed5 LgJ4VmA6WfAVRvfxqezzrZvLTner4LazLvSZwfTmRY03FwGzdMpZ17fAKYuMzUk+UxSR eGeA== X-Gm-Message-State: APjAAAWCsLB3RuAybJHLLzpR7QsP2JApPvz/mD0+bdDt05j+ZxAGXaO+ CTI3Qz1cbW5HWv4k4M0i44mlAJNwUGk= X-Google-Smtp-Source: APXvYqxB8t3OO+Hk+A6mJqpJRAxbX9yChJfL6kq6ukDjNcwxsPp3wR8rYIRijlai2QxXC2pgePIcxQ== X-Received: by 2002:adf:e984:: with SMTP id h4mr2222937wrm.32.1556559487300; Mon, 29 Apr 2019 10:38:07 -0700 (PDT) Received: from raver.teknoraver.net (net-93-70-69-135.cust.vodafonedsl.it. [93.70.69.135]) by smtp.gmail.com with ESMTPSA id z7sm86811wml.40.2019.04.29.10.38.05 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 29 Apr 2019 10:38:06 -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" Subject: [PATCH net] cls_matchall: avoid panic when receiving a packet before filter set Date: Mon, 29 Apr 2019 19:38:05 +0200 Message-Id: <20190429173805.4455-1-mcroce@redhat.com> X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When a matchall 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: # tc qdisc replace dev eth0 ingress # tc filter add dev eth0 parent ffff: matchall action gact drop Unable to handle kernel NULL pointer dereference at virtual address 0000000000000034 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 = 00000000a623d530 [0000000000000034] pgd=0000000000000000, pud=0000000000000000 Internal error: Oops: 96000005 [#1] SMP Modules linked in: cls_matchall sch_ingress nls_iso8859_1 nls_cp437 vfat fat m25p80 spi_nor mtd xhci_plat_hcd xhci_hcd phy_generic sfp mdio_i2c usbcore i2c_mv64xxx marvell10g mvpp2 usb_common spi_orion mvmdio i2c_core sbsa_gwdt phylink ip_tables x_tables autofs4 Process ksoftirqd/0 (pid: 9, stack limit = 0x0000000009de7d62) CPU: 0 PID: 9 Comm: ksoftirqd/0 Not tainted 5.1.0-rc6 #21 Hardware name: Marvell 8040 MACCHIATOBin Double-shot (DT) pstate: 40000005 (nZcv daif -PAN -UAO) pc : mall_classify+0x28/0x78 [cls_matchall] lr : tcf_classify+0x78/0x138 sp : ffffff80109db9d0 x29: ffffff80109db9d0 x28: ffffffc426058800 x27: 0000000000000000 x26: ffffffc425b0dd00 x25: 0000000020000000 x24: 0000000000000000 x23: ffffff80109dbac0 x22: 0000000000000001 x21: ffffffc428ab5100 x20: ffffffc425b0dd00 x19: ffffff80109dbac0 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: ffffffbf108ad288 x12: dead000000000200 x11: 00000000f0000000 x10: 0000000000000001 x9 : ffffffbf1089a220 x8 : 0000000000000001 x7 : ffffffbebffaa950 x6 : 0000000000000000 x5 : 000000442d6ba000 x4 : 0000000000000000 x3 : ffffff8008735ad8 x2 : ffffff80109dbac0 x1 : ffffffc425b0dd00 x0 : ffffff8010592078 Call trace: mall_classify+0x28/0x78 [cls_matchall] tcf_classify+0x78/0x138 __netif_receive_skb_core+0x29c/0xa20 __netif_receive_skb_one_core+0x34/0x60 __netif_receive_skb+0x28/0x78 netif_receive_skb_internal+0x2c/0xc0 napi_gro_receive+0x1a0/0x1d8 mvpp2_poll+0x928/0xb18 [mvpp2] net_rx_action+0x108/0x378 __do_softirq+0x128/0x320 run_ksoftirqd+0x44/0x60 smpboot_thread_fn+0x168/0x1b0 kthread+0x12c/0x130 ret_from_fork+0x10/0x1c Code: aa0203f3 aa1e03e0 d503201f f9400684 (b9403480) ---[ end trace fc71e2ef7b8ab5a5 ]--- Kernel panic - not syncing: Fatal exception in interrupt SMP: stopping secondary CPUs Kernel Offset: disabled CPU features: 0x002,00002000 Memory Limit: none Rebooting in 1 seconds.. Fix this by creating a dummy action in the init which is skipped by mall_classify, and remove it upon the first action set in mall_change. Doing this we avoid adding an extra check in the classify. Signed-off-by: Matteo Croce --- net/sched/cls_matchall.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/net/sched/cls_matchall.c b/net/sched/cls_matchall.c index a13bc351a414..8aaa9d80c2ca 100644 --- a/net/sched/cls_matchall.c +++ b/net/sched/cls_matchall.c @@ -27,6 +27,10 @@ struct cls_mall_head { struct rcu_work rwork; }; +static const struct cls_mall_head match_none = { + .flags = TCA_CLS_FLAGS_SKIP_SW +}; + static int mall_classify(struct sk_buff *skb, const struct tcf_proto *tp, struct tcf_result *res) { @@ -42,6 +46,8 @@ static int mall_classify(struct sk_buff *skb, const struct tcf_proto *tp, static int mall_init(struct tcf_proto *tp) { + rcu_assign_pointer(tp->root, &match_none); + return 0; } @@ -114,7 +120,7 @@ static void mall_destroy(struct tcf_proto *tp, bool rtnl_held, { struct cls_mall_head *head = rtnl_dereference(tp->root); - if (!head) + if (head == &match_none) return; tcf_unbind_filter(tp, &head->res); @@ -132,7 +138,7 @@ static void *mall_get(struct tcf_proto *tp, u32 handle) { struct cls_mall_head *head = rtnl_dereference(tp->root); - if (head && head->handle == handle) + if (head != &match_none && head->handle == handle) return head; return NULL; @@ -178,7 +184,7 @@ static int mall_change(struct net *net, struct sk_buff *in_skb, if (!tca[TCA_OPTIONS]) return -EINVAL; - if (head) + if (head != &match_none) return -EEXIST; err = nla_parse_nested(tb, TCA_MATCHALL_MAX, tca[TCA_OPTIONS], @@ -253,7 +259,7 @@ static void mall_walk(struct tcf_proto *tp, struct tcf_walker *arg, if (arg->count < arg->skip) goto skip; - if (!head) + if (head == &match_none) return; if (arg->fn(tp, head, arg) < 0) arg->stop = 1; @@ -298,7 +304,7 @@ static int mall_dump(struct net *net, struct tcf_proto *tp, void *fh, struct nlattr *nest; int cpu; - if (!head) + if (!head || head == &match_none) return skb->len; t->tcm_handle = head->handle;