Re: [PATCH 4.4 02/96] s390/runtime instrumention: fix possible memory corruption

Greg Kroah-Hartman
2017-12-05T17:08:40Z

On Tue, Dec 05, 2017 at 05:02:32PM +0000, Ben Hutchings wrote:
> On Tue, 2017-11-28 at 11:22 +0100, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch.ï¿½ï¿½If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > From: Heiko Carstens <heiko.carstens@de.ibm.com>
> >
> > commit d6e646ad7cfa7034d280459b2b2546288f247144 upstream.
> [...]
> > --- a/arch/s390/kernel/runtime_instr.c
> > +++ b/arch/s390/kernel/runtime_instr.c
> > @@ -47,11 +47,13 @@ void exit_thread_runtime_instr(void)
> > ï¿½{
> > ï¿½ struct task_struct *task = current;
> > ï¿½
> > + preempt_disable();
> > ï¿½ if (!task->thread.ri_cb)
> > ï¿½ return;
>
> This return path now leaves preemption disabled. This seems to have
> been fixed upstream by commit 8d9047f8b967 "s390/runtime
> instrumentation: simplify task exit handling".

"simplify" doesn't seem to imply "fixes a bug" :)

Heiko, should I also queue this patch up?

thanks Ben for the review.

greg k-h