[dm-devel] libmultipath: fix NULL dereference in get_be64

[lixiaokeng]

>>
>> cli_add_path
>>    ->ev_add_path
>>       ->add_map_with_path
>>          ->adopt_paths
>>             ->pathinfo
>>                ->filter_property
>>                ->return PATHINFO_SKIPPED,
>>             ->pp->mpp is NULL and not be set
>>             ->return 0
> 
> This returns 0, but add_map_with_path() has this code to check whether
> the path passed to it was actually added to the new map:
> 
> 	if (adopt_paths(vecs->pathvec, mpp) ||
> 	    find_slot(vecs->pathvec, pp) == -1)
> 		goto out;  -> return NULL
> 
> So ev_add_path() should have seen a NULL return from
> add_map_with_path(), should not have set start_waiter, and failed. 
> 

I'm sorry for a big mistake in my stack. As the code is optimized, pathinfo
return PATHINFO_SKIPPED after finish filter_property when I use gdb. It
happens acctualy in:
2141			if (pp->bus == SYSFS_BUS_SCSI &&
2142			    pp->sg_id.proto_id == SCSI_PROTOCOL_USB &&
2143			    !conf->allow_usb_devices) {
2144				condlog(3, "%s: skip USB device %s", pp->dev,
2145					pp->tgt_node_name);
2146				return PATHINFO_SKIPPED;
2147			}
2148		}

Stack:
cli_add_path
   ->ev_add_path
      ->add_map_with_path
         ->adopt_paths
            ->pathinfo
               ->pp->bus == SYSFS_BUS_SCSI
               ->return PATHINFO_SKIPPED,
            ->pp->mpp is NULL and not be set
            ->return 0
      ->mpath_pr_event_handle
         ->get_be64 //pp->mpp is dereference

If you think my patch is ok, I will resend it.

Regards
Lixiaokeng