Evgeniy Polyakov wrote: > On Wed, Apr 18, 2007 at 12:16:18PM +0400, Pavel Emelianov ([EMAIL PROTECTED]) > wrote: > >>Sorry, I forgot to put netdev and David in Cc when I first sent it. >> >>There is a race between netlink_dump_start() and netlink_release() >>that can lead to the situation when a netlink socket with non-zero >>callback is freed. > > > Out of curiosity, why not to fix a netlink_dump_start() to remove > callback in error path, since in 'no-error' path it removes it in > netlink_dump().
It already does (netlink_destroy_callback), but that doesn't help with this race though since without this patch we don't enter the error path. > And, btw, can release method be called while socket is being used, I > thought about proper reference counters should prevent this, but not > 100% sure with RCU dereferencing of the descriptor. The problem is asynchronous processing of the dump request in the context of a different process. Process requests a dump, message is queued and process returns from sendmsg since some other process is already processing the queue. Then the process closes the socket, resulting in netlink_release being called. When the dump request is finally processed the race Pavel described might happen. This can only happen for netlink families that use mutex_try_lock for queue processing of course. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
