From nobody Wed Feb 11 14:44:56 2026 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 8B08AC77B7F for ; Mon, 8 May 2023 13:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233829AbjEHNnL (ORCPT ); Mon, 8 May 2023 09:43:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232748AbjEHNnI (ORCPT ); Mon, 8 May 2023 09:43:08 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1298EE5F; Mon, 8 May 2023 06:43:07 -0700 (PDT) Received: from kwepemi500026.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QFMrT3sfHzsRGW; Mon, 8 May 2023 21:41:13 +0800 (CST) Received: from localhost.localdomain (10.175.104.82) by kwepemi500026.china.huawei.com (7.221.188.247) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Mon, 8 May 2023 21:43:03 +0800 From: Dong Chenchen To: , , , CC: , , , , , Dong Chenchen Subject: [PATCH -next] net: nsh: Use correct mac_offset to unwind gso skb in nsh_gso_segment() Date: Mon, 8 May 2023 21:42:58 +0800 Message-ID: <20230508134258.496465-1-dongchenchen2@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.104.82] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi500026.china.huawei.com (7.221.188.247) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" As the call trace shows, skb_panic was caused by wrong skb->mac_header in nsh_gso_segment(): invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 3 PID: 2737 Comm: syz Not tainted 6.3.0-next-20230505 #1 RIP: 0010:skb_panic+0xda/0xe0 call Trace: skb_push+0x91/0xa0 nsh_gso_segment+0x4f3/0x570 skb_mac_gso_segment+0x19e/0x270 __skb_gso_segment+0x1e8/0x3c0 validate_xmit_skb+0x452/0x890 validate_xmit_skb_list+0x99/0xd0 sch_direct_xmit+0x294/0x7c0 __dev_queue_xmit+0x16f0/0x1d70 packet_xmit+0x185/0x210 packet_snd+0xc15/0x1170 packet_sendmsg+0x7b/0xa0 sock_sendmsg+0x14f/0x160 The root cause is: nsh_gso_segment() use skb->network_header - nhoff to reset mac_header in skb_gso_error_unwind() if inner-layer protocol gso fails. However, skb->network_header may be reset by inner-layer protocol gso function e.g. mpls_gso_segment. skb->mac_header reset by the inaccurate network_header will be larger than skb headroom. nsh_gso_segment nhoff =3D skb->network_header - skb->mac_header; __skb_pull(skb,nsh_len) skb_mac_gso_segment mpls_gso_segment skb_reset_network_header(skb);//skb->network_header+=3Dnsh_len return -EINVAL; skb_gso_error_unwind skb_push(skb, nsh_len); skb->mac_header =3D skb->network_header - nhoff; // skb->mac_header > skb->headroom, cause skb_push panic Use correct mac_offset to restore mac_header to fix it. Fixes: c411ed854584 ("nsh: add GSO support") Signed-off-by: Dong Chenchen --- net/nsh/nsh.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/nsh/nsh.c b/net/nsh/nsh.c index e9ca007718b7..17433b115058 100644 --- a/net/nsh/nsh.c +++ b/net/nsh/nsh.c @@ -78,6 +78,7 @@ static struct sk_buff *nsh_gso_segment(struct sk_buff *sk= b, { struct sk_buff *segs =3D ERR_PTR(-EINVAL); unsigned int nsh_len, mac_len; + u16 mac_offset; __be16 proto; int nhoff; =20 @@ -103,13 +104,13 @@ static struct sk_buff *nsh_gso_segment(struct sk_buff= *skb, skb_reset_mac_header(skb); skb->mac_len =3D proto =3D=3D htons(ETH_P_TEB) ? ETH_HLEN : 0; skb->protocol =3D proto; + mac_offset =3D skb->network_header - nhoff; =20 features &=3D NETIF_F_SG; segs =3D skb_mac_gso_segment(skb, features); if (IS_ERR_OR_NULL(segs)) { skb_gso_error_unwind(skb, htons(ETH_P_NSH), nsh_len, - skb->network_header - nhoff, - mac_len); + mac_offset, mac_len); goto out; } =20 --=20 2.25.1