Re: kernel crash when device rose set down

[f6bvp <f6bvp@free.fr>]

Hello Ralf,

This is to publicize the patch you made against an important
bug responsible of kernel panic when seting rose device down..

Bernard

Le 15/06/2015 12:39, f6bvp a écrit :
> Bingo Ralf !
>
> You have found the bug.
>
> 73 de Bernard, f6bvp
>
>
> Le 15/06/2015 03:21, Ralf Baechle a écrit :
>> On Sun, Jun 14, 2015 at 12:06:53AM +0200, f6bvp wrote:
>>
>>> After neutralizing the three lines I could execute command
>>> "ifconfig rose down" without any issue.
>>> I guess the loop ran through the list of possible rose devices
>>> from rose9 to rose0.
>>> -----------------------
>>> [  214.831371] DEBUG: Passed rose_close 131
>>> [  214.831462] DEBUG: Passed rose_device_event 217
>>> [  214.831465] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831467] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831470] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831472] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831474] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831476] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831478] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831480] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831483] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831485] DEBUG: Passed rose_kill_by_device 192
>>> [  214.831487] DEBUG: Passed rose_kill_by_device 199
>>> [root@RaspBerry-Pi-f6bvp-8 bernard]#
>>> -----------------------
>>> And the bug may be there, for I think  it should not try to 
>>> disconnect ALL
>>> possible rose devices but
>>> only the one we want ?
>> The look is iterating through all ROSE sockets shutting down the ones
>> that are associated with the device being shut down.  That is correct.
>> What's not correct is that the code is trying to reduce the socket's
>> neighbour's use counter unconditionally - there might not even be a
>> neighbour such as for example for a listening socket.
>>
>> Can you test this please?
>>
>> 73,
>>
>>    Ralf
>>
>> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
>>
>> diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
>> index 8ae6030..dd304bc 100644
>> --- a/net/rose/af_rose.c
>> +++ b/net/rose/af_rose.c
>> @@ -192,7 +192,8 @@ static void rose_kill_by_device(struct net_device 
>> *dev)
>>             if (rose->device == dev) {
>>               rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0);
>> -            rose->neighbour->use--;
>> +            if (rose->neighbour)
>> +                rose->neighbour->use--;
>>               rose->device = NULL;
>>           }
>>       }
>

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