Re: DoS with POSIX file locks?

[Miklos Szeredi]

> Right.  Um.  I took it out back in March 2003 after enough people
> convinced me it wasn't worth trying to account for all the memory
> processes use, and the userbeans project would take care of it anyway.
> Haha.
> 
> It's hard to fix the accounting.  You have to deal with one thread
> allocating the lock, and then a different thread freeing it.  We never
> actually accounted for posix locks (which are the ones we really needed
> to!) and on occasion had current->locks go negative, with all kinds of
> associated badness.

Things look fairly straightforward if the accounting is done in
files_struct instead of task_struct.  At least for POSIX locks.  I
haven't looked at flocks or leases yet.

steal_locks() might cause problems, but that function should be gotten
rid of anyway.

Miklos
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/