Re: [PATCH-next] sched: Fix Null pointer derefrence

[Khaled Romdhani]

On Sat, May 15, 2021 at 11:02:38PM +0200, Peter Zijlstra wrote:
> On Sat, May 15, 2021 at 05:46:45PM +0100, Khaled ROMDHANI wrote:
> > The 'curr' variable could be NULL and derefrenced by
> > pick_next_entity. Fix this by adding a check that prevent
> > the invocation of pick_next_entity with a NULL passed argument.
> 
> And why exactly is that a problem?
>
Within pick_next_entity, we could have 'left = curr'. 
Thus the function wakeup_preempt_entity which is invoked 
from pick_next_entity, derefrence the the sched entity 'left' 
that may be a NULL passed argument.