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

Dmitry Vyukov
2018-10-12T14:42:26Z

On Thu, Oct 11, 2018 at 4:28 PM, Dominique Martinet
<asmadeus@codewreck.org> wrote:
> Dmitry Vyukov wrote on Thu, Oct 11, 2018:
>> > 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 :)