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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 B1E76C43387 for ; Wed, 26 Dec 2018 22:52:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78A73214D8 for ; Wed, 26 Dec 2018 22:52:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545864769; bh=8vMR+yx+nUF3zVs9FziAzgXN75/JIfgQv0/0HQHuMFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=llcFBO1Ga2bsdxwojmvki8osBnkrOUbDiKzIi8uqW9j+pLGXxbF39BH/xsYHRS3o/ 3lw0zZ35lBTt3/EJtHgyn4CJ/Ato7FVxAz17xkZX8UPA5ThyFtc0SkzMNv3piekOsR SknxUBnH5sdaqZZvi6BLVLJi9FSyY8sl5+gNVIh8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729972AbeLZWwr (ORCPT ); Wed, 26 Dec 2018 17:52:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:37046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727658AbeLZWg5 (ORCPT ); Wed, 26 Dec 2018 17:36:57 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5406F218FE; Wed, 26 Dec 2018 22:36:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545863817; bh=8vMR+yx+nUF3zVs9FziAzgXN75/JIfgQv0/0HQHuMFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D1MtOA64Nc75PGc6rk0XiJLni7ExDDktuF66L2xua5FqsVV72lSVBJaqQiySR6E7R lryd3saRhAXdtQ21owazSSPjljuqQJc/N78C4UJm6oOMDn3tWmIAuH8Vto+MgLOcaA dQToGrwZvgrRSWo8dNFrXpIsOr/14Mk1myv8fXtE= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Florian Westphal , Pablo Neira Ayuso , Sasha Levin , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 36/97] netfilter: nat: can't use dst_hold on noref dst Date: Wed, 26 Dec 2018 17:34:56 -0500 Message-Id: <20181226223557.149329-36-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181226223557.149329-1-sashal@kernel.org> References: <20181226223557.149329-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Florian Westphal [ Upstream commit 542fbda0f08f1cbbc250f9e59f7537649651d0c8 ] The dst entry might already have a zero refcount, waiting on rcu list to be free'd. Using dst_hold() transitions its reference count to 1, and next dst release will try to free it again -- resulting in a double free: WARNING: CPU: 1 PID: 0 at include/net/dst.h:239 nf_xfrm_me_harder+0xe7/0x130 [nf_nat] RIP: 0010:nf_xfrm_me_harder+0xe7/0x130 [nf_nat] Code: 48 8b 5c 24 60 65 48 33 1c 25 28 00 00 00 75 53 48 83 c4 68 5b 5d 41 5c c3 85 c0 74 0d 8d 48 01 f0 0f b1 0a 74 86 85 c0 75 f3 <0f> 0b e9 7b ff ff ff 29 c6 31 d2 b9 20 00 48 00 4c 89 e7 e8 31 27 Call Trace: nf_nat_ipv4_out+0x78/0x90 [nf_nat_ipv4] nf_hook_slow+0x36/0xd0 ip_output+0x9f/0xd0 ip_forward+0x328/0x440 ip_rcv+0x8a/0xb0 Use dst_hold_safe instead and bail out if we cannot take a reference. Fixes: a4c2fd7f7891 ("net: remove DST_NOCACHE flag") Reported-by: Martin Zaharinov Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/nf_nat_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index e2b196054dfc..2268b10a9dcf 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -117,7 +117,8 @@ int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family) dst = skb_dst(skb); if (dst->xfrm) dst = ((struct xfrm_dst *)dst)->route; - dst_hold(dst); + if (!dst_hold_safe(dst)) + return -EHOSTUNREACH; if (sk && !net_eq(net, sock_net(sk))) sk = NULL; -- 2.19.1