AX.25 uses sock_queue_rcv_skb() to queue an iframe received packet.
This routine writes NULL to the socket buffer device structure
pointer. The socket buffer is subsequently serviced by
__netif_receiv_skb_core() which dereferences the device structure
pointer & segfaults.
The fix puts the ax25 device structure pointer back in the socket
buffer struct after sock_queue_rcv_skb() is called.
To trigger the segfault setup an ax.25 device (ax0) then run net2kiss
(net2kiss -v -i ax0 /dev/ptmx). In another console make an ax.25
connection (call udr0 jnbbs). Within 2 received packets a segfault
will occur.
Please submit to -stable.
Signed-off-by: Basil Gunn <basil@xxxxxxxxxxxxx>
---
net/ax25/ax25_in.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/ax25/ax25_in.c b/net/ax25/ax25_in.c
index bb5a0e4..417f21a 100644
--- a/net/ax25/ax25_in.c
+++ b/net/ax25/ax25_in.c
@@ -144,10 +144,15 @@ int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
if ((!ax25->pidincl && ax25->sk->sk_protocol == pid) ||
ax25->pidincl) {
+ /* Will set socket buffer device struct pointer,
+ * skb->dev to NULL
+ */
if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
queued = 1;
else
ax25->condition |= AX25_COND_OWN_RX_BUSY;
+
+ skb->dev = ax25->ax25_dev->dev;
}
}
--
2.1.4
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