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 X-Spam-Level: X-Spam-Status: No, score=-10.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E631EC433E0 for ; Fri, 8 Jan 2021 10:19:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DE0023716 for ; Fri, 8 Jan 2021 10:19:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727118AbhAHKTm (ORCPT ); Fri, 8 Jan 2021 05:19:42 -0500 Received: from www62.your-server.de ([213.133.104.62]:33198 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725984AbhAHKTm (ORCPT ); Fri, 8 Jan 2021 05:19:42 -0500 Received: from sslproxy01.your-server.de ([78.46.139.224]) by www62.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92.3) (envelope-from ) id 1kxoqv-0004vR-1g; Fri, 08 Jan 2021 11:18:41 +0100 Received: from [85.7.101.30] (helo=pc-9.home) by sslproxy01.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kxoqu-0005en-NO; Fri, 08 Jan 2021 11:18:40 +0100 Subject: Re: [PATCH net v3] net: fix use-after-free when UDP GRO with shared fraglist To: Dongseok Yi , "David S. Miller" , Willem de Bruijn Cc: Jakub Kicinski , Miaohe Lin , Paolo Abeni , Florian Westphal , Al Viro , Guillaume Nault , Yunsheng Lin , Steffen Klassert , Yadu Kishore , Marco Elver , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, namkyu78.kim@samsung.com References: <1609979953-181868-1-git-send-email-dseok.yi@samsung.com> <1610072918-174177-1-git-send-email-dseok.yi@samsung.com> From: Daniel Borkmann Message-ID: <9d8cccfe-21d1-4bd2-0cce-4e8af2dd6ef6@iogearbox.net> Date: Fri, 8 Jan 2021 11:18:39 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <1610072918-174177-1-git-send-email-dseok.yi@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.4/26042/Thu Jan 7 13:37:55 2021) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 1/8/21 3:28 AM, Dongseok Yi wrote: > skbs in fraglist could be shared by a BPF filter loaded at TC. If TC > writes, it will call skb_ensure_writable -> pskb_expand_head to create > a private linear section for the head_skb. And then call > skb_clone_fraglist -> skb_get on each skb in the fraglist. > > skb_segment_list overwrites part of the skb linear section of each > fragment itself. Even after skb_clone, the frag_skbs share their > linear section with their clone in PF_PACKET. > > Both sk_receive_queue of PF_PACKET and PF_INET (or PF_INET6) can have > a link for the same frag_skbs chain. If a new skb (not frags) is > queued to one of the sk_receive_queue, multiple ptypes can see and > release this. It causes use-after-free. > > [ 4443.426215] ------------[ cut here ]------------ > [ 4443.426222] refcount_t: underflow; use-after-free. > [ 4443.426291] WARNING: CPU: 7 PID: 28161 at lib/refcount.c:190 > refcount_dec_and_test_checked+0xa4/0xc8 > [ 4443.426726] pstate: 60400005 (nZCv daif +PAN -UAO) > [ 4443.426732] pc : refcount_dec_and_test_checked+0xa4/0xc8 > [ 4443.426737] lr : refcount_dec_and_test_checked+0xa0/0xc8 > [ 4443.426808] Call trace: > [ 4443.426813] refcount_dec_and_test_checked+0xa4/0xc8 > [ 4443.426823] skb_release_data+0x144/0x264 > [ 4443.426828] kfree_skb+0x58/0xc4 > [ 4443.426832] skb_queue_purge+0x64/0x9c > [ 4443.426844] packet_set_ring+0x5f0/0x820 > [ 4443.426849] packet_setsockopt+0x5a4/0xcd0 > [ 4443.426853] __sys_setsockopt+0x188/0x278 > [ 4443.426858] __arm64_sys_setsockopt+0x28/0x38 > [ 4443.426869] el0_svc_common+0xf0/0x1d0 > [ 4443.426873] el0_svc_handler+0x74/0x98 > [ 4443.426880] el0_svc+0x8/0xc > > Fixes: 3a1296a38d0c (net: Support GRO/GSO fraglist chaining.) > Signed-off-by: Dongseok Yi > Acked-by: Willem de Bruijn Acked-by: Daniel Borkmann