Re: NULL primary_path

[Vlad Yasevich <vyasevich@gmail.com>]

On 03/07/2013 10:29 AM, Neil Horman wrote:
> On Thu, Mar 07, 2013 at 03:52:35PM +0100, Cristian Constantin wrote:
>> On Wed, Mar 06, 2013 at 08:53:02PM -0500, Vlad Yasevich wrote:
>>> On 03/06/2013 05:57 PM, Karl Heiss wrote:
>>>> I am getting kernel panics due to a NULL dereference in
>>>> sctp_getsockopt_sctp_status() when calling getsockopt() with
>>>> SCTP_STATUS immediately after establishing a connection.  This occurs
>>>> when transport = asoc->peer.primary_path; is NULL and transport is
>>>> later dereferenced.  Is there any way that an association would be
>>>> present but have no primary_path?
>>>
>>> No, that shouldn't happen.  The very first transport that is added
>>> to the association is assigned to the primary_path.  Primary_path can
>>> never be null since the association must have at least 1 transport and
>>> that 1 transport will always be primary.
>>
>> cristian: hi!
>>
>> but, vlad, at least in 2.6.30.2 (which I have on my hdd with
>> the "tags" already computed), sctp_getsockopt_primary_addr() is a little
>> bit more conservative and does:
>>
>>      ...
>>      asoc = sctp_id2assoc(sk, prim.ssp_assoc_id);
>>      if (!asoc)
>>          return -EINVAL;
>>
>>      if (!asoc->peer.primary_path)
>>          return -ENOTCONN;
>>      ...
>>
>> any idea if is there any big difference btw. the two getsockopt()s? behind
>> them, everything is assumed to be asynch., right? (in the sense that
>> the assoc. can come and go at any time)
>>
> All paths that touch primary_path hold the associated socket lock for the socket
> that owns the transport path, so there shouldn't be any changing of the primary
> path while accessing it here, at least not in the upstream kernel.

Right.  I don't this that condition is possible.  Association can't live 
without at least 1 transport and that 1 transport will always be primary.

-vlad

>
> Regards
> Neil
>
>> thanks!
>> bye now!
>> cristian
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