[PATCH] futex: futex_find_get_task remove credentails check

[Michal Hocko]

On Wed 30-06-10 09:01:15, Michal Hocko wrote:
> On Tue 29-06-10 09:41:02, Linus Torvalds wrote:
> > On Tue, Jun 29, 2010 at 1:42 AM, Michal Hocko <mhocko@xxxxxxx> wrote:
> > >
> > > futex_find_get_task is currently used (through lookup_pi_state) from two
> > > contexts, futex_requeue and futex_lock_pi_atomic. While credentials check
> > > makes sense in the first code path, the second one is more problematic
> > > because this check requires that the PI lock holder (pid parameter) has
> > > the same uid and euid as the process's euid which is trying to lock the
> > > same futex (current).
> > 
> > So exactly why does it make sense to check the credentials in the
> > first code path then? 
> 
> I though that requeue needs this for security reasons (don't let requeue
> process for other user), but when I thought about that again you are
> right and the only what matters should be accessibility of the shared
> memory.

And here is the patch which does the thing.

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