netdev - Re: [PATCH net v3] netrom: linearize and validate lengths in nr_rx

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Message-ID: <20250905174450.3953023d@kernel.org>
Date: Fri, 5 Sep 2025 17:44:50 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Stanislav Fort <stanislav.fort@...le.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
 pabeni@...hat.com, horms@...nel.org, linux-hams@...r.kernel.org,
 linux-kernel@...r.kernel.org, security@...nel.org, Stanislav Fort
 <disclosure@...le.com>
Subject: Re: [PATCH net v3] netrom: linearize and validate lengths in
 nr_rx_frame()

On Wed,  3 Sep 2025 21:19:15 +0300 Stanislav Fort wrote:
> Linearize skb and add targeted length checks in nr_rx_frame() to avoid out-of-bounds reads and potential use-after-free when processing malformed NET/ROM frames.
> 
> - Linearize skb and require at least NR_NETWORK_LEN + NR_TRANSPORT_LEN (20 bytes) before reading network/transport fields.
> - For existing sockets path, ensure NR_CONNACK includes the window byte (>= 21 bytes).
> - For CONNREQ handling, ensure window (byte 20) and user address (bytes 21-27) are present (>= 28 bytes).
> - Maintain existing BPQ extension handling:
>   - NR_CONNACK len == 22 implies 1 extra byte (TTL)
>   - NR_CONNREQ len == 37 implies 2 extra bytes (timeout)
> 
> Suggested-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Stanislav Fort <disclosure@...le.com>
> Signed-off-by: Stanislav Fort <disclosure@...le.com>

Thanks for the fix! The commit message needs a bit of touching up..

Please wrap it at 74 chars.

Please add a Fixes tag pointing to the commit which introduced the
bugs. Quite possibly Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") in area
of the code base.

Please remove the Reported-by:, it's implicit that the author discovered
the bug if no explicit reported-by tag is provided.

Please add the review tag from Eric when reposting.
-- 
pw-bot: cr