On Wed, Jan 2, 2019 at 12:12 AM Bernard Pidoux [off-list ref] wrote:

Hi David,

In my previous message I should have reported the following patch rather than the one I reported.

The reason is that the bug is better explained here :

https://marc.info/?l=linux-hams&m=154478673812818&w=2

and  I hope the new proposed patch is more convenient.


Bernard


Le 01/01/2019 à 23:39, Bernard Pidoux a écrit :

Hi David,

As you already know I am still looking for the simplest way to configure a kernel rose failure situation when rose_route_frame is called with a NULL pointer.

Could you explain with full details how to have "TCP/IP over AX.25 fully configured" ?

More specifically how can we configure rose device without NOARP ? This is not the case when performing Dmitry Vyukov :

# ip link set dev rose0 address 11:22:33:44:55
# ip link set dev rose0 up

73 de Bernard, f6bvp


Le 08/12/2018 à 17:23, David Ranch a écrit :

Hello Bernard, Everyone,

Yes, I've seen a similar behavior with another program I have here that broadcasts on all live TCP/IP interfaces when it loads.  That all depends if you have TCP/IP over AX.25 fully configured on your machine.  If you do, this cp,,amd should key up your radio to send out an ARP:

    ping -b -c 1 <broadcast IP on your ROSE or AX.25 interface>
   --
   d710: fm KI6ZHD to QST ctl UI pid=CC(IP) len 84
   IP: len 84 44.4.10.39->44.4.10.127 ihl 20 ttl 64 DF prot ICMP
   ICMP: type Echo Request id 50814 seq 1
   P�.\
   �~.
   ................ !"#$%&'()*+,-./01234567
   --

Btw, I've been aware of this ROSE panic issue for some time and I'm pretty sure I forwarded those details on to you but that was many years ago.  Another way to reproduce a ROSE panic is, if I remember correctly, you remove the backing AX.25 interface's connection (say killing kisssattach for ax0) on a ROSE interface that has an IP, that will also panic the kernel every time.

--David
KI6ZHD

+mailing lists

Hi Bernard,

I've provided a bit more information on what I did here:
https://groups.google.com/d/msg/syzkaller/v-4B3zoBC-4/MVgYoeSQCgAJ

I really did not do anything fancy.

FWIW I had to do the following locally just to prevent rose from
crashing my machine all the time. I don't know if it's the right fix
or not, I just used this as stop-gap.

diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c
index 77e9f85a2c92..218308a3c02c 100644
--- a/net/rose/rose_route.c
+++ b/net/rose/rose_route.c

@@ -874,6 +874,8 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25)
             skb->data[ROSE_CALL_REQ_ADDR_LEN_OFF] !=
             ROSE_CALL_REQ_ADDR_LEN_VAL))
                return res;
+       if (ax25 == NULL)
+               return res;
        src_addr  = (rose_address *)(skb->data + ROSE_CALL_REQ_SRC_ADDR_OFF);
        dest_addr = (rose_address *)(skb->data + ROSE_CALL_REQ_DEST_ADDR_OFF);

rose_xmit calls rose_route_frame with ax25==NULL, then
rose_route_frame uses ax25 without any checks.