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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Nikolay Aleksandrov <razor@blackwall.org>
Cc: Netdev <netdev@vger.kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martynas Pumputis <m@lambda.lt>,
	WireGuard mailing list <wireguard@lists.zx2c4.com>,
	Jakub Kicinski <kuba@kernel.org>,
	David Miller <davem@davemloft.net>,
	stable <stable@vger.kernel.org>
Subject: Re: [PATCH net 1/2] wireguard: device: fix metadata_dst xmit null pointer dereference
Date: Thu, 14 Apr 2022 13:58:04 +0200	[thread overview]
Message-ID: <CAHmME9qZyz26gnfcZCjAiLhYqZ9LwJN1VZ+3rgGmhxJYrGvZCw@mail.gmail.com> (raw)
In-Reply-To: <20220414104458.3097244-2-razor@blackwall.org>

Hi Nikolay,

On Thu, Apr 14, 2022 at 12:45 PM Nikolay Aleksandrov
<razor@blackwall.org> wrote:
> When we try to transmit an skb with md_dst attached through wireguard
> we hit a null pointer dereference[1] 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
> fallback 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.

Thanks for the patch. Will queue up this patch #1 in the wireguard
tree and send it out to net.git not before too long.

Jason

  parent reply	other threads:[~2022-04-14 11:58 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-14 10:44 [PATCH net 0/2] wireguard: device: fix metadata_dst xmit null pointer dereference Nikolay Aleksandrov
2022-04-14 10:44 ` [PATCH net 1/2] " Nikolay Aleksandrov
2022-04-14 11:28   ` Daniel Borkmann
2022-04-14 11:58   ` Jason A. Donenfeld [this message]
2022-04-14 10:44 ` [PATCH net 2/2] wireguard: selftests: add metadata_dst xmit selftest Nikolay Aleksandrov
2022-04-14 12:06   ` Jason A. Donenfeld
2022-04-14 12:12     ` Nikolay Aleksandrov
2022-04-14 12:24       ` Jason A. Donenfeld

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