On Wed, Sep 3, 2025 at 11:19 AM Stanislav Fort [off-list ref] 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@google.com>
Reported-by: Stanislav Fort <redacted>
Signed-off-by: Stanislav Fort <redacted>
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Reviewed-by: Eric Dumazet <edumazet@google.com>