From: Miquel Raynal <miquel.raynal@bootlin•com>
To: Eric Dumazet <edumazet@google•com>
Cc: "David S . Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>,
Paolo Abeni <pabeni@redhat•com>,
Simon Horman <horms@kernel•org>,
netdev@vger•kernel.org, eric.dumazet@gmail•com,
syzbot+f13c19f75e1097abd116@syzkaller•appspotmail.com,
Alexander Aring <alex.aring@gmail•com>,
Stefan Schmidt <stefan@datenfreihafen•org>
Subject: Re: [PATCH net] ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit()
Date: Wed, 03 Jun 2026 17:45:25 +0200 [thread overview]
Message-ID: <87h5njzkyy.fsf@bootlin.com> (raw)
In-Reply-To: <20260603072955.4032221-1-edumazet@google.com> (Eric Dumazet's message of "Wed, 3 Jun 2026 07:29:55 +0000")
Hi Eric,
On 03/06/2026 at 07:29:55 GMT, Eric Dumazet <edumazet@google•com> wrote:
> The aoe driver (or similar) generates a non-IPv6 packet
> (e.g., ETH_P_AOE) and queues it for transmission via dev_queue_xmit()
> on a 6LoWPAN interface (configured by the user or test case).
>
> Since the packet is not IPv6, the 6LoWPAN header_ops->create function
> (lowpan_header_create or header_create) returns early without initializing
> the lowpan_addr_info structure in the skb headroom.
>
> In the transmit function (lowpan_xmit), the driver calls lowpan_header
> (or setup_header) which unconditionally copies and uses the lowpan_addr_info
> from the headroom, which contains uninitialized data.
>
> Fix this by dropping non IPv6 packets.
I am not sure I fully grasped the syzbot report. The problem may happen
because an interface can be configured as a 6lowpan interface, which in
this case should not transmit the packet, but there are other possible
configurations which would just work and accept ETH_P_AOE packets
(whatever that is). Is this correct? If so, then this indeed looks like
the best approach,
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin•com>
But otherwise I guess this fix would totally prevent the AOE driver
from working correctly, so I just want to double check my understanding.
Thanks,
Miquèl
next prev parent reply other threads:[~2026-06-03 15:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-03 7:29 [PATCH net] ieee802154: 6lowpan: only accept IPv6 packets in lowpan_xmit() Eric Dumazet
2026-06-03 15:45 ` Miquel Raynal [this message]
2026-06-03 15:57 ` Eric Dumazet
2026-06-03 16:04 ` Miquel Raynal
2026-06-04 16:00 ` patchwork-bot+netdevbpf
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