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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C50BC433F5 for ; Fri, 25 Mar 2022 15:14:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359857AbiCYPPw (ORCPT ); Fri, 25 Mar 2022 11:15:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376342AbiCYPMv (ORCPT ); Fri, 25 Mar 2022 11:12:51 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A68965407; Fri, 25 Mar 2022 08:09:29 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 39EB2B82889; Fri, 25 Mar 2022 15:09:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A0161C340E9; Fri, 25 Mar 2022 15:09:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1648220966; bh=W7LKArX9yRiNSPg8Ifp/MUekT2A0flsCrjHTHh07QOg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zc/XlwC/k9Chn4ip5hteEzuIvviS3TlTIfVp4ohNvJL2Yu1Afh7BBbaE/CYaqvIEy u8qwk4Elp0LwZmbIhPcag8xvyi/3lhfzxSJFqfeGRywssm+I/5Irk6B7UyYz17TPZa 44FZ9V2rRv7HNnO6P2rYEndMMh4wYJ1Ilb8+e4K4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com, Tadeusz Struk , Willem de Bruijn , Jakub Kicinski Subject: [PATCH 5.10 02/38] net: ipv6: fix skb_over_panic in __ip6_append_data Date: Fri, 25 Mar 2022 16:04:46 +0100 Message-Id: <20220325150419.830695569@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220325150419.757836392@linuxfoundation.org> References: <20220325150419.757836392@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: stable@vger.kernel.org From: Tadeusz Struk commit 5e34af4142ffe68f01c8a9acae83300f8911e20c upstream. Syzbot found a kernel bug in the ipv6 stack: LINK: https://syzkaller.appspot.com/bug?id=205d6f11d72329ab8d62a610c44c5e7e25415580 The reproducer triggers it by sending a crafted message via sendmmsg() call, which triggers skb_over_panic, and crashes the kernel: skbuff: skb_over_panic: text:ffffffff84647fb4 len:65575 put:65575 head:ffff888109ff0000 data:ffff888109ff0088 tail:0x100af end:0xfec0 dev: Update the check that prevents an invalid packet with MTU equal to the fregment header size to eat up all the space for payload. The reproducer can be found here: LINK: https://syzkaller.appspot.com/text?tag=ReproC&x=1648c83fb00000 Reported-by: syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com Signed-off-by: Tadeusz Struk Acked-by: Willem de Bruijn Link: https://lore.kernel.org/r/20220310232538.1044947-1-tadeusz.struk@linaro.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1500,8 +1500,8 @@ static int __ip6_append_data(struct sock sizeof(struct frag_hdr) : 0) + rt->rt6i_nfheader_len; - if (mtu < fragheaderlen || - ((mtu - fragheaderlen) & ~7) + fragheaderlen < sizeof(struct frag_hdr)) + if (mtu <= fragheaderlen || + ((mtu - fragheaderlen) & ~7) + fragheaderlen <= sizeof(struct frag_hdr)) goto emsgsize; maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen -