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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 D3C9DC433E6 for ; Fri, 22 Jan 2021 14:55:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABF8A239EF for ; Fri, 22 Jan 2021 14:55:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728697AbhAVOzl (ORCPT ); Fri, 22 Jan 2021 09:55:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:39306 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728362AbhAVOXp (ORCPT ); Fri, 22 Jan 2021 09:23:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 470D123BA7; Fri, 22 Jan 2021 14:18:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611325091; bh=K6QMxmbf5P4UjZK0d/rqUv5vhavfHqu/4/tEK3AlVQw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ioNICJWWUK5FreUjjdIhsy7H0lEUkw5iq4EM39WkEIjma3Tq3OWJ2zEgXTVywAeOc YO9+HIj2g0tdr+KB0ojzB6c/mwYUsryASmmHLWo8KXo5mIn6mbanp6eJspxnlb660O hknGQKapX/iPEsl2MwDPz9GFC8FqdQsB42IwstGI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dongseok Yi , Willem de Bruijn , Daniel Borkmann , Jakub Kicinski Subject: [PATCH 5.10 12/43] net: fix use-after-free when UDP GRO with shared fraglist Date: Fri, 22 Jan 2021 15:12:28 +0100 Message-Id: <20210122135736.141811031@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210122135735.652681690@linuxfoundation.org> References: <20210122135735.652681690@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dongseok Yi [ Upstream commit 53475c5dd856212e91538a9501162e821cc1f791 ] 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 Link: https://lore.kernel.org/r/1610072918-174177-1-git-send-email-dseok.yi@samsung.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/core/skbuff.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3648,7 +3648,8 @@ struct sk_buff *skb_segment_list(struct unsigned int delta_truesize = 0; unsigned int delta_len = 0; struct sk_buff *tail = NULL; - struct sk_buff *nskb; + struct sk_buff *nskb, *tmp; + int err; skb_push(skb, -skb_network_offset(skb) + offset); @@ -3658,11 +3659,28 @@ struct sk_buff *skb_segment_list(struct nskb = list_skb; list_skb = list_skb->next; + err = 0; + if (skb_shared(nskb)) { + tmp = skb_clone(nskb, GFP_ATOMIC); + if (tmp) { + consume_skb(nskb); + nskb = tmp; + err = skb_unclone(nskb, GFP_ATOMIC); + } else { + err = -ENOMEM; + } + } + if (!tail) skb->next = nskb; else tail->next = nskb; + if (unlikely(err)) { + nskb->next = list_skb; + goto err_linearize; + } + tail = nskb; delta_len += nskb->len;