Commit 8034f361 authored by Bernard Pidoux's avatar Bernard Pidoux Committed by Greg Kroah-Hartman

net/rose: fix NULL ax25_cb kernel panic

[ Upstream commit b0cf029234f9b18e10703ba5147f0389c382bccc ]

When an internally generated frame is handled by rose_xmit(),
rose_route_frame() is called:

        if (!rose_route_frame(skb, NULL)) {
                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
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.

Built kernel with CONFIG_ROSE=y.
Signed-off-by: default avatarBernard Pidoux <>
Acked-by: default avatarDmitry Vyukov <>
Cc: "David S. Miller" <>
Cc: Ralf Baechle <>
Cc: Bernard Pidoux <>
Signed-off-by: default avatarDavid S. Miller <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent ce29e8a2
......@@ -848,6 +848,7 @@ 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)
......@@ -865,6 +866,10 @@ 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 &&
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