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 C5408C6FD18 for ; Tue, 18 Apr 2023 12:27:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231396AbjDRM1g (ORCPT ); Tue, 18 Apr 2023 08:27:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231408AbjDRM1a (ORCPT ); Tue, 18 Apr 2023 08:27:30 -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 364B959F6 for ; Tue, 18 Apr 2023 05:27:06 -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 8B87363189 for ; Tue, 18 Apr 2023 12:26:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DD9BC4339C; Tue, 18 Apr 2023 12:26:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681820810; bh=xsB/HPINQqlXQJ/xerlXWajiwBq+3RSzz4ZFWcV0EzI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bu14m5Dr2dYF7VeqN3zI4i9Amq/K2N29M3geEku+CrBOEGSkF2HZDYYblmOSdfPYJ A7b8m0pmE5f+EKWk9NhwmSsQSmFlmDrEff6tEHA3UQW7CKEsKVn6RjC9+ld8nHNSUL wMNIjP0NZcibkgAO40nGFCYjaxsiR5H8x6nno7hY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+d373d60fddbdc915e666@syzkaller.appspotmail.com, Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.19 10/57] icmp: guard against too small mtu Date: Tue, 18 Apr 2023 14:21:10 +0200 Message-Id: <20230418120259.084090655@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120258.713853188@linuxfoundation.org> References: <20230418120258.713853188@linuxfoundation.org> User-Agent: quilt/0.67 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: Eric Dumazet [ Upstream commit 7d63b67125382ff0ffdfca434acbc94a38bd092b ] syzbot was able to trigger a panic [1] in icmp_glue_bits(), or more exactly in skb_copy_and_csum_bits() There is no repro yet, but I think the issue is that syzbot manages to lower device mtu to a small value, fooling __icmp_send() __icmp_send() must make sure there is enough room for the packet to include at least the headers. We might in the future refactor skb_copy_and_csum_bits() and its callers to no longer crash when something bad happens. [1] kernel BUG at net/core/skbuff.c:3343 ! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 15766 Comm: syz-executor.0 Not tainted 6.3.0-rc4-syzkaller-00039-gffe78bbd5121 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:skb_copy_and_csum_bits+0x798/0x860 net/core/skbuff.c:3343 Code: f0 c1 c8 08 41 89 c6 e9 73 ff ff ff e8 61 48 d4 f9 e9 41 fd ff ff 48 8b 7c 24 48 e8 52 48 d4 f9 e9 c3 fc ff ff e8 c8 27 84 f9 <0f> 0b 48 89 44 24 28 e8 3c 48 d4 f9 48 8b 44 24 28 e9 9d fb ff ff RSP: 0018:ffffc90000007620 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 00000000000001e8 RCX: 0000000000000100 RDX: ffff8880276f6280 RSI: ffffffff87fdd138 RDI: 0000000000000005 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 00000000000001e8 R11: 0000000000000001 R12: 000000000000003c R13: 0000000000000000 R14: ffff888028244868 R15: 0000000000000b0e FS: 00007fbc81f1c700(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2df43000 CR3: 00000000744db000 CR4: 0000000000150ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: icmp_glue_bits+0x7b/0x210 net/ipv4/icmp.c:353 __ip_append_data+0x1d1b/0x39f0 net/ipv4/ip_output.c:1161 ip_append_data net/ipv4/ip_output.c:1343 [inline] ip_append_data+0x115/0x1a0 net/ipv4/ip_output.c:1322 icmp_push_reply+0xa8/0x440 net/ipv4/icmp.c:370 __icmp_send+0xb80/0x1430 net/ipv4/icmp.c:765 ipv4_send_dest_unreach net/ipv4/route.c:1239 [inline] ipv4_link_failure+0x5a9/0x9e0 net/ipv4/route.c:1246 dst_link_failure include/net/dst.h:423 [inline] arp_error_report+0xcb/0x1c0 net/ipv4/arp.c:296 neigh_invalidate+0x20d/0x560 net/core/neighbour.c:1079 neigh_timer_handler+0xc77/0xff0 net/core/neighbour.c:1166 call_timer_fn+0x1a0/0x580 kernel/time/timer.c:1700 expire_timers+0x29b/0x4b0 kernel/time/timer.c:1751 __run_timers kernel/time/timer.c:2022 [inline] Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+d373d60fddbdc915e666@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet Link: https://lore.kernel.org/r/20230330174502.1915328-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/icmp.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index aa179e6461e17..af0ddaa55e431 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -759,6 +759,11 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info, room = 576; room -= sizeof(struct iphdr) + icmp_param.replyopts.opt.opt.optlen; room -= sizeof(struct icmphdr); + /* Guard against tiny mtu. We need to include at least one + * IP network header for this message to make any sense. + */ + if (room <= (int)sizeof(struct iphdr)) + goto ende; icmp_param.data_len = skb_in->len - icmp_param.offset; if (icmp_param.data_len > room) -- 2.39.2