* [PATCH net v3] netrom: linearize and validate lengths in nr_rx_frame() [not found] <20250902112652.26293-1-disclosure@aisle.com> @ 2025-09-03 18:19 ` Stanislav Fort 2025-09-05 10:47 ` Eric Dumazet 2025-09-06 0:44 ` Jakub Kicinski 0 siblings, 2 replies; 3+ messages in thread From: Stanislav Fort @ 2025-09-03 18:19 UTC (permalink / raw) To: netdev Cc: davem, edumazet, kuba, pabeni, horms, linux-hams, linux-kernel, security, Stanislav Fort 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 <disclosure@aisle.com> Signed-off-by: Stanislav Fort <disclosure@aisle.com> --- net/netrom/af_netrom.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c index 3331669d8e33..f0660dd6d3b0 100644 --- a/net/netrom/af_netrom.c +++ b/net/netrom/af_netrom.c @@ -885,6 +885,11 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev) * skb->data points to the netrom frame start */ + if (skb_linearize(skb)) + return 0; + if (skb->len < NR_NETWORK_LEN + NR_TRANSPORT_LEN) + return 0; + src = (ax25_address *)(skb->data + 0); dest = (ax25_address *)(skb->data + 7); @@ -927,6 +932,11 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev) } if (sk != NULL) { + if (frametype == NR_CONNACK && + skb->len < NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1) { + sock_put(sk); + return 0; + } bh_lock_sock(sk); skb_reset_transport_header(skb); @@ -961,10 +971,14 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev) return 0; } - sk = nr_find_listener(dest); + /* Need window (byte 20) and user address (bytes 21-27) */ + if (skb->len < NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1 + AX25_ADDR_LEN) + return 0; user = (ax25_address *)(skb->data + 21); + sk = nr_find_listener(dest); + if (sk == NULL || sk_acceptq_is_full(sk) || (make = nr_make_new(sk)) == NULL) { nr_transmit_refusal(skb, 0); -- 2.39.3 (Apple Git-146) ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH net v3] netrom: linearize and validate lengths in nr_rx_frame() 2025-09-03 18:19 ` [PATCH net v3] netrom: linearize and validate lengths in nr_rx_frame() Stanislav Fort @ 2025-09-05 10:47 ` Eric Dumazet 2025-09-06 0:44 ` Jakub Kicinski 1 sibling, 0 replies; 3+ messages in thread From: Eric Dumazet @ 2025-09-05 10:47 UTC (permalink / raw) To: Stanislav Fort Cc: netdev, davem, kuba, pabeni, horms, linux-hams, linux-kernel, security, Stanislav Fort On Wed, Sep 3, 2025 at 11:19 AM Stanislav Fort <stanislav.fort@aisle.com> 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 <disclosure@aisle.com> > Signed-off-by: Stanislav Fort <disclosure@aisle.com> > --- Reviewed-by: Eric Dumazet <edumazet@google.com> ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net v3] netrom: linearize and validate lengths in nr_rx_frame() 2025-09-03 18:19 ` [PATCH net v3] netrom: linearize and validate lengths in nr_rx_frame() Stanislav Fort 2025-09-05 10:47 ` Eric Dumazet @ 2025-09-06 0:44 ` Jakub Kicinski 1 sibling, 0 replies; 3+ messages in thread From: Jakub Kicinski @ 2025-09-06 0:44 UTC (permalink / raw) To: Stanislav Fort Cc: netdev, davem, edumazet, pabeni, horms, linux-hams, linux-kernel, security, Stanislav Fort 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@google.com> > Reported-by: Stanislav Fort <disclosure@aisle.com> > Signed-off-by: Stanislav Fort <disclosure@aisle.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 ^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-09-03 18:19 ` [PATCH net v3] netrom: linearize and validate lengths in nr_rx_frame() Stanislav Fort
2025-09-05 10:47 ` Eric Dumazet
2025-09-06 0:44 ` Jakub Kicinski
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