Users locking memory using futexes

From: Jamie Lokier (lk@tantalophile.demon.co.uk)
Date: Mon Nov 11 2002 - 22:46:48 EST


Perez-Gonzalez, Inaky wrote:
> [...] each time you lock a futex you are pinning the containing page
> into physical memory, that would cause that if you have, for
> example, 4000 futexes locked in 4000 different pages, there is going
> to be 4 MB of memory locked in [...]

Ouch! It looks to me like userspace can use FUTEX_FD to lock many
pages of memory, achieving the same as mlock() but without the
resource checks.

Denial of service attack?

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



This archive was generated by hypermail 2b29 : Fri Nov 15 2002 - 22:00:24 EST