From patchwork Thu Oct 27 10:24:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Ziyang Xuan (William)" X-Patchwork-Id: 13021915 X-Patchwork-Delegate: kuba@kernel.org 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 BBD86C67871 for ; Thu, 27 Oct 2022 10:25:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234187AbiJ0KZD (ORCPT ); Thu, 27 Oct 2022 06:25:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234169AbiJ0KZB (ORCPT ); Thu, 27 Oct 2022 06:25:01 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22D332D742; Thu, 27 Oct 2022 03:24:55 -0700 (PDT) Received: from canpemm500006.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4MyhWM2Vkcz15M45; Thu, 27 Oct 2022 18:19:59 +0800 (CST) Received: from localhost.localdomain (10.175.104.82) by canpemm500006.china.huawei.com (7.192.105.130) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 27 Oct 2022 18:24:53 +0800 From: Ziyang Xuan To: , , , , , , CC: , Subject: [PATCH net] ipv6/gro: fix an out of bounds memory bug in ipv6_gro_receive() Date: Thu, 27 Oct 2022 18:24:49 +0800 Message-ID: <20221027102449.926410-1-william.xuanziyang@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.104.82] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500006.china.huawei.com (7.192.105.130) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org IPv6 packets without NEXTHDR_NONE extension header can make continuous __skb_pull() until pskb_may_pull() failed in ipv6_gso_pull_exthdrs(). That results in a big value of skb_gro_offset(), and after __skb_push() in ipv6_gro_receive(), skb->data will less than skb->head, an out of bounds memory bug occurs. That will trigger the problem as following: ================================================================== BUG: KASAN: use-after-free in eth_type_trans+0x100/0x260 ... Call trace: dump_backtrace+0xd8/0x130 show_stack+0x1c/0x50 dump_stack_lvl+0x64/0x7c print_address_description.constprop.0+0xbc/0x2e8 print_report+0x100/0x1e4 kasan_report+0x80/0x120 __asan_load8+0x78/0xa0 eth_type_trans+0x100/0x260 napi_gro_frags+0x164/0x550 tun_get_user+0xda4/0x1270 tun_chr_write_iter+0x74/0x130 do_iter_readv_writev+0x130/0x1ec do_iter_write+0xbc/0x1e0 vfs_writev+0x13c/0x26c Add comparison between skb->data - skb_gro_offset() and skb->head and exception handler before __skb_push() to fix the bug. Fixes: 86911732d399 ("gro: Avoid copying headers of unmerged packets") Signed-off-by: Ziyang Xuan --- net/ipv6/ip6_offload.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c index 3ee345672849..6659ccf25387 100644 --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -237,6 +237,10 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head, proto = ipv6_gso_pull_exthdrs(skb, proto); skb_gro_pull(skb, -skb_transport_offset(skb)); skb_reset_transport_header(skb); + if (unlikely(skb_headroom(skb) < skb_gro_offset(skb))) { + kfree_skb(skb); + return ERR_PTR(-EINPROGRESS); + } __skb_push(skb, skb_gro_offset(skb)); ops = rcu_dereference(inet6_offloads[proto]);