[PATCH] [ROSE] NULL ax25_cb kernel panic
When an internally generated frame is handled by rose_xmit(),
rose_route_frame() is called:
if (!rose_route_frame(skb, NULL)) {
dev_kfree_skb(skb);
stats->tx_errors++;
return NETDEV_TX_OK;
}
We have the same code sequence in Net/Rom where an internally generated
frame is handled by nr_xmit() calling nr_route_frame(skb, NULL).
However, in this function NULL argument is tested while it is not in
rose_route_frame().
Then kernel panic occurs later on when calling ax25cmp() with a NULL
ax25_cb argument as reported many times and recently with syzbot.
We need to test if ax25 is NULL before using it.
Here is the patch:
diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c
index 77e9f85a2c92..7f075255a372 100644
--- a/net/rose/rose_route.c
+++ b/net/rose/rose_route.c
@@ -850,6 +850,7 @@ void rose_link_device_down(struct net_device *dev)
/*
* Route a frame to an appropriate AX.25 connection.
+ * a NULL ax25_cb indicates an internally generated frame.
*/
int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
{
@@ -867,6 +868,10 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb
*ax25)
if (skb->len < ROSE_MIN_LEN)
return res;
+
+ if (!ax25)
+ return rose_loopback_queue(skb, NULL);
+
frametype = skb->data[2];
lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
if (frametype == ROSE_CALL_REQUEST &&
Reported-by:[email protected]
Signed-off-by: Bernard Pidoux, f6bvp <[email protected]>
