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 D576DC001E0 for ; Fri, 28 Jul 2023 12:01:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236434AbjG1MBB (ORCPT ); Fri, 28 Jul 2023 08:01:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236098AbjG1MAw (ORCPT ); Fri, 28 Jul 2023 08:00:52 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12FAA44A6; Fri, 28 Jul 2023 05:00:23 -0700 (PDT) Received: from canpemm500007.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RC5lf0tWnz1GDHQ; Fri, 28 Jul 2023 19:59:26 +0800 (CST) Received: from [10.174.179.215] (10.174.179.215) by canpemm500007.china.huawei.com (7.192.104.62) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Fri, 28 Jul 2023 20:00:21 +0800 Subject: Re: [PATCH] ip6mr: Fix skb_under_panic in ip6mr_cache_report() To: Eric Dumazet CC: , , , , , , References: <20230728100035.32092-1-yuehaibing@huawei.com> From: YueHaibing Message-ID: <1578283a-37fc-3679-25fe-3650cf150d11@huawei.com> Date: Fri, 28 Jul 2023 20:00:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.215] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500007.china.huawei.com (7.192.104.62) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/7/28 18:50, Eric Dumazet wrote: > On Fri, Jul 28, 2023 at 12:01 PM Yue Haibing wrote: >> >> skbuff: skb_under_panic: text:ffffffff88771f69 len:56 put:-4 >> head:ffff88805f86a800 data:ffff887f5f86a850 tail:0x88 end:0x2c0 dev:pim6reg >> ------------[ cut here ]------------ >> > >> When setup a vlan device on dev pim6reg, DAD ns packet may sent on reg_vif_xmit(). >> reg_vif_xmit() >> ip6mr_cache_report() >> skb_push(skb, -skb_network_offset(pkt));//skb_network_offset(pkt) is 4 >> And skb_push declar as this: >> void *skb_push(struct sk_buff *skb, unsigned int len); >> skb->data -= len; >> //0xffff888f5f86a84c - 0xfffffffc = 0xffff887f5f86a850 >> skb->data is set to 0xffff887f5f86a850, which is invalid mem addr, lead to skb_push() fails. >> >> Fixes: 14fb64e1f449 ("[IPV6] MROUTE: Support PIM-SM (SSM).") >> Signed-off-by: Yue Haibing >> --- >> net/ipv6/ip6mr.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c >> index cc3d5ad17257..ee9c2ff8b0e4 100644 >> --- a/net/ipv6/ip6mr.c >> +++ b/net/ipv6/ip6mr.c >> @@ -1051,9 +1051,9 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, >> int ret; >> >> #ifdef CONFIG_IPV6_PIMSM_V2 >> + int nhoff = skb_network_offset(pkt); >> if (assert == MRT6MSG_WHOLEPKT || assert == MRT6MSG_WRMIFWHOLE) >> - skb = skb_realloc_headroom(pkt, -skb_network_offset(pkt) >> - +sizeof(*msg)); >> + skb = skb_realloc_headroom(pkt, -nhoff + sizeof(*msg)); >> else >> #endif >> skb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(*msg), GFP_ATOMIC); >> @@ -1073,7 +1073,8 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, >> And all this only to mangle msg->im6_msgtype and >> to set msg->im6_mbz to "mbz" :-) >> */ >> - skb_push(skb, -skb_network_offset(pkt)); >> + skb->data += nhoff; >> + skb->len -= nhoff; > > __skb_pull(skb, nhoff); Thanks， will do this in v2. > >> >> skb_push(skb, sizeof(*msg)); >> skb_reset_transport_header(skb); >> -- >> 2.34.1 >> > . >