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 6927AC433FE for ; Thu, 21 Apr 2022 13:48:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354918AbiDUNv3 (ORCPT ); Thu, 21 Apr 2022 09:51:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1387532AbiDUNv1 (ORCPT ); Thu, 21 Apr 2022 09:51:27 -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 7377C387B0; Thu, 21 Apr 2022 06:48:37 -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 EB7FF61D43; Thu, 21 Apr 2022 13:48:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 920B5C385A1; Thu, 21 Apr 2022 13:48:35 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="oOBY5cE9" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1650548913; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gmw2affTTW8Jrsi1py2DH/poP+25yl94U+xIteuoEyo=; b=oOBY5cE9ReqqNWmEIrcpJ7ew7ylwRbkqGwrrLEOUmld7YcTghFLOnYNsFo/ZFaJNx9AHqG GnsULGFpSJ1AJSyZLlBrjaFV5gCP6gSic/42jrbDNaGKpaja9MC/Khj9aapFTRlH4uepnw JiDr0oAtR5dcGobOetHXMXpIXCHmCxc= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id c330bc87 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Thu, 21 Apr 2022 13:48:33 +0000 (UTC) From: "Jason A. Donenfeld" To: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org Cc: Nikolay Aleksandrov , stable@vger.kernel.org, Martynas Pumputis , Daniel Borkmann , "Jason A . Donenfeld" Subject: [PATCH net 2/2] wireguard: device: check for metadata_dst with skb_valid_dst() Date: Thu, 21 Apr 2022 15:48:05 +0200 Message-Id: <20220421134805.279118-3-Jason@zx2c4.com> In-Reply-To: <20220421134805.279118-1-Jason@zx2c4.com> References: <20220421134805.279118-1-Jason@zx2c4.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Nikolay Aleksandrov When we try to transmit an skb with md_dst attached through wireguard we hit a null pointer dereference in wg_xmit() due to the use of dst_mtu() which calls into dst_blackhole_mtu() which in turn tries to dereference dst->dev. Since wireguard doesn't use md_dsts we should use skb_valid_dst(), which checks for DST_METADATA flag, and if it's set, then falls back to wireguard's device mtu. That gives us the best chance of transmitting the packet; otherwise if the blackhole netdev is used we'd get ETH_MIN_MTU. [ 263.693506] BUG: kernel NULL pointer dereference, address: 00000000000000e0 [ 263.693908] #PF: supervisor read access in kernel mode [ 263.694174] #PF: error_code(0x0000) - not-present page [ 263.694424] PGD 0 P4D 0 [ 263.694653] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 263.694876] CPU: 5 PID: 951 Comm: mausezahn Kdump: loaded Not tainted 5.18.0-rc1+ #522 [ 263.695190] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014 [ 263.695529] RIP: 0010:dst_blackhole_mtu+0x17/0x20 [ 263.695770] Code: 00 00 00 0f 1f 44 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 47 10 48 83 e0 fc 8b 40 04 85 c0 75 09 48 8b 07 <8b> 80 e0 00 00 00 c3 66 90 0f 1f 44 00 00 48 89 d7 be 01 00 00 00 [ 263.696339] RSP: 0018:ffffa4a4422fbb28 EFLAGS: 00010246 [ 263.696600] RAX: 0000000000000000 RBX: ffff8ac9c3553000 RCX: 0000000000000000 [ 263.696891] RDX: 0000000000000401 RSI: 00000000fffffe01 RDI: ffffc4a43fb48900 [ 263.697178] RBP: ffffa4a4422fbb90 R08: ffffffff9622635e R09: 0000000000000002 [ 263.697469] R10: ffffffff9b69a6c0 R11: ffffa4a4422fbd0c R12: ffff8ac9d18b1a00 [ 263.697766] R13: ffff8ac9d0ce1840 R14: ffff8ac9d18b1a00 R15: ffff8ac9c3553000 [ 263.698054] FS: 00007f3704c337c0(0000) GS:ffff8acaebf40000(0000) knlGS:0000000000000000 [ 263.698470] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 263.698826] CR2: 00000000000000e0 CR3: 0000000117a5c000 CR4: 00000000000006e0 [ 263.699214] Call Trace: [ 263.699505] [ 263.699759] wg_xmit+0x411/0x450 [ 263.700059] ? bpf_skb_set_tunnel_key+0x46/0x2d0 [ 263.700382] ? dev_queue_xmit_nit+0x31/0x2b0 [ 263.700719] dev_hard_start_xmit+0xd9/0x220 [ 263.701047] __dev_queue_xmit+0x8b9/0xd30 [ 263.701344] __bpf_redirect+0x1a4/0x380 [ 263.701664] __dev_queue_xmit+0x83b/0xd30 [ 263.701961] ? packet_parse_headers+0xb4/0xf0 [ 263.702275] packet_sendmsg+0x9a8/0x16a0 [ 263.702596] ? _raw_spin_unlock_irqrestore+0x23/0x40 [ 263.702933] sock_sendmsg+0x5e/0x60 [ 263.703239] __sys_sendto+0xf0/0x160 [ 263.703549] __x64_sys_sendto+0x20/0x30 [ 263.703853] do_syscall_64+0x3b/0x90 [ 263.704162] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 263.704494] RIP: 0033:0x7f3704d50506 [ 263.704789] Code: 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 11 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 72 c3 90 55 48 83 ec 30 44 89 4c 24 2c 4c 89 [ 263.705652] RSP: 002b:00007ffe954b0b88 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 263.706141] RAX: ffffffffffffffda RBX: 0000558bb259b490 RCX: 00007f3704d50506 [ 263.706544] RDX: 000000000000004a RSI: 0000558bb259b7b2 RDI: 0000000000000003 [ 263.706952] RBP: 0000000000000000 R08: 00007ffe954b0b90 R09: 0000000000000014 [ 263.707339] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe954b0b90 [ 263.707735] R13: 000000000000004a R14: 0000558bb259b7b2 R15: 0000000000000001 [ 263.708132] [ 263.708398] Modules linked in: bridge netconsole bonding [last unloaded: bridge] [ 263.708942] CR2: 00000000000000e0 Cc: stable@vger.kernel.org Fixes: e7096c131e51 ("net: WireGuard secure network tunnel") Link: https://github.com/cilium/cilium/issues/19428 Reported-by: Martynas Pumputis Signed-off-by: Nikolay Aleksandrov Acked-by: Daniel Borkmann Signed-off-by: Jason A. Donenfeld --- drivers/net/wireguard/device.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c index 0fad1331303c..aa9a7a5970fd 100644 --- a/drivers/net/wireguard/device.c +++ b/drivers/net/wireguard/device.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -167,7 +168,7 @@ static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev) goto err_peer; } - mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu; + mtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu; __skb_queue_head_init(&packets); if (!skb_is_gso(skb)) { -- 2.35.1