From patchwork Fri Jul 15 03:22:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: shaozhengchao X-Patchwork-Id: 12918701 X-Patchwork-Delegate: bpf@iogearbox.net 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 DB6D9C43334 for ; Fri, 15 Jul 2022 03:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241267AbiGODSK (ORCPT ); Thu, 14 Jul 2022 23:18:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229809AbiGODSI (ORCPT ); Thu, 14 Jul 2022 23:18:08 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C1AC76E85; Thu, 14 Jul 2022 20:18:07 -0700 (PDT) Received: from dggpeml500026.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Lkc1X0yKrz1L943; Fri, 15 Jul 2022 11:15:28 +0800 (CST) Received: from huawei.com (10.175.101.6) by dggpeml500026.china.huawei.com (7.185.36.106) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 15 Jul 2022 11:18:03 +0800 From: Zhengchao Shao To: , , , , , , , CC: , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v3,bpf-next] bpf: Don't redirect packets with invalid pkt_len Date: Fri, 15 Jul 2022 11:22:33 +0800 Message-ID: <20220715032233.230507-1-shaozhengchao@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml500026.china.huawei.com (7.185.36.106) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Syzbot found an issue [1]: fq_codel_drop() try to drop a flow whitout any skbs, that is, the flow->head is null. The root cause, as the [2] says, is because that bpf_prog_test_run_skb() run a bpf prog which redirects empty skbs. So we should determine whether the length of the packet modified by bpf prog or others like bpf_prog_test is valid before forwarding it directly. LINK: [1] https://syzkaller.appspot.com/bug?id=0b84da80c2917757915afa89f7738a9d16ec96c5 LINK: [2] https://www.spinics.net/lists/netdev/msg777503.html Reported-by: syzbot+7a12909485b94426aceb@syzkaller.appspotmail.com Signed-off-by: Zhengchao Shao --- v2: need move checking to convert___skb_to_skb and add debug info v1: should not check len in fast path include/linux/skbuff.h | 11 +++++++++++ net/bpf/test_run.c | 3 +++ net/core/dev.c | 1 + 3 files changed, 15 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index f6a27ab19202..8ea41ad0786b 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2459,6 +2459,17 @@ static inline void skb_set_tail_pointer(struct sk_buff *skb, const int offset) #endif /* NET_SKBUFF_DATA_USES_OFFSET */ +static inline void skb_assert_len(struct sk_buff *skb) +{ +#ifdef CONFIG_DEBUG_NET + if (unlikely(!skb->len)) { + pr_err("%s\n", __func__); + skb_dump(KERN_ERR, skb, false); + WARN_ON_ONCE(1); + } +#endif /* CONFIG_DEBUG_NET */ +} + /* * Add data to an sk_buff */ diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 2ca96acbc50a..dc9dc0bedca0 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -955,6 +955,9 @@ static int convert___skb_to_skb(struct sk_buff *skb, struct __sk_buff *__skb) { struct qdisc_skb_cb *cb = (struct qdisc_skb_cb *)skb->cb; + if (!skb->len) + return -EINVAL; + if (!__skb) return 0; diff --git a/net/core/dev.c b/net/core/dev.c index d588fd0a54ce..716df64fcfa5 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4168,6 +4168,7 @@ int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) bool again = false; skb_reset_mac_header(skb); + skb_assert_len(skb); if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP)) __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED);