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 8664EC433F5 for ; Mon, 21 Mar 2022 22:56:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231712AbiCUW5g (ORCPT ); Mon, 21 Mar 2022 18:57:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231324AbiCUW5A (ORCPT ); Mon, 21 Mar 2022 18:57:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C622537764A; Mon, 21 Mar 2022 15:37:23 -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 dfw.source.kernel.org (Postfix) with ESMTPS id ABF7261574; Mon, 21 Mar 2022 21:53:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04734C36AE7; Mon, 21 Mar 2022 21:53:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647899628; bh=TtYaq9/U0mcGokV5YP+KOEgHqM7Tv1eSAcP4xaQd3s8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K7ZRKrTzQJ6uvFq9cJFgNmzIX0iOlArc1srlpzLQl/IiT2kM1+Gn1Mpr1ckCPetDk dJycRsmCVeqo+hXWKNpijK5OD5k2DA/cI/u9VKV/AMHoUbbHLsM28i/W9YGNISUwV+ gAkJQa5PQFTiZoXV2NTjpaiJwM/fSgbM3z+Xff97RATdsCVtHwAH2v4+6n4FZSikhg NRPJUtSwyZZcvADZ8H/XpBWwfG3n7S78/9qEOmg89pLMFffOZfKAahk6VzSpqgHyWk a5yZ9WJp+CrVeSAlPJJIh00MOquiSL4JXBKUgjknhBwBc1FPqqQQE776SY0th7BYSp 1cxNOEA1tgsug== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Tadeusz Struk , syzbot+e223cf47ec8ae183f2a0@syzkaller.appspotmail.com, Willem de Bruijn , Jakub Kicinski , Sasha Levin , davem@davemloft.net, yoshfuji@linux-ipv6.org, dsahern@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 2/2] net: ipv6: fix skb_over_panic in __ip6_append_data Date: Mon, 21 Mar 2022 17:53:43 -0400 Message-Id: <20220321215343.490600-2-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220321215343.490600-1-sashal@kernel.org> References: <20220321215343.490600-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tadeusz Struk [ Upstream commit 5e34af4142ffe68f01c8a9acae83300f8911e20c ] 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: Sasha Levin --- net/ipv6/ip6_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 55be18cae35b..775901abe678 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1329,8 +1329,8 @@ static int __ip6_append_data(struct sock *sk, 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 - -- 2.34.1