Re: 9p/RDMA for syzkaller (Was: BUG: corrupted list in p9_read_work)

On Thu, Oct 11, 2018 at 4:28 PM, Dominique Martinet
[off-list ref] wrote:

Dmitry Vyukov wrote on Thu, Oct 11, 2018:

quoted

quoted

Now we are talking!
We generally assume that all modules are simply compiled into kernel.
At least that's we have on syzbot. If somebody can't compile them in,
we can suggest to add modprobe into init.
So this boils down to just writing to /sys/module/rdma_rxe/parameters/add.

This fails for me:

root@syzkaller:~# echo -n syz1 > /sys/module/rdma_rxe/parameters/add
[20992.905406] rdma_rxe: interface syz1 not found
bash: echo: write error: Invalid argument

Works here, I just did:

[root@f2 ~]# modprobe rdma_rxe
[root@f2 ~]# echo -n ens3 > /sys/module/rdma_rxe/parameters/add

dmesg says:
[   35.595534] rdma_rxe: set rxe0 active
[   35.595541] rdma_rxe: added rxe0 to ens3


Actually for a dummy interface if I try the echo directly the echo
works, and a verb device is created, and I just confirmed I can use
it... so not sure why rxe_cfg said EINVAL earlier...

[root@f2 ~]# ip link add dummy0 type dummy
[root@f2 ~]# ip link set dummy0 up
[root@f2 ~]# ip addr add 10.1.1.1/24 dev dummy0
[root@f2 ~]# modprobe rdma_rxe
[root@f2 ~]# echo -n dummy0 > /sys/module/rdma_rxe/parameters/add


(then using my test client:
[root@f2 src]# ./rcat -s
INFO:  trans_rdma.c (879), msk_cma_event_handler: CONNECT_REQUEST
INFO:  trans_rdma.c (862), msk_cma_event_handler: ESTABLISHED
INFO:  trans_rdma.c (917), msk_cma_event_handler: DISCONNECT EVENT...

[root@f2 src]# ./rcat -c 10.1.1.1
INFO:  trans_rdma.c (862), msk_cma_event_handler: ESTABLISHED
^C
)


I assume your syz1 interface is a tap device as you were saying earlier?
Got anything in dmesg?

Umm... nope, just a random string.
Don't assume any prior knowledge on my side :)