Re: [PATCH -next v2] unix stream: Fix use-after-free crashes

Le mardi 06 septembre 2011 à 12:33 -0700, Tim Chen a écrit :

Yes, I think locking the sendmsg for the entire duration of
unix_stream_sendmsg makes a lot of sense.  It simplifies the logic a lot
more.  I'll try to cook something up in the next couple of days.

Thats not really possible, we cant hold a spinlock and call
sock_alloc_send_skb() and/or memcpy_fromiovec(), wich might sleep.

You would need to prepare the full skb list, then :
- stick the ref on the last skb of the list.

Transfert the whole skb list in other->sk_receive_queue in one go,
instead of one after another.

Unfortunately, this would break streaming (big send(), and another
thread doing the receive)

Listen, I am wondering why hackbench even triggers SCM code. This is
really odd. We should not have a _single_ pid/cred ref/unref at all.