On Thu, Dec 14, 2017 at 3:26 PM, Thomas Gleixner <t...@linutronix.de> wrote:
> On Tue, 12 Dec 2017, Greg KH wrote:
>
>> On Tue, Dec 05, 2017 at 11:58:07AM -0800, Kees Cook wrote:
>> > On Thu, Nov 30, 2017 at 4:57 AM, Thomas Gleixner <t...@linutronix.de>
>> > wrote:
>> > > On Thu, 30 Nov 2017, Alexey Dobriyan wrote:
>> > >
>> > >> [cc security@]
>> > >> 100% oops with interrupts disabled by nobody
>> > >> or kernel memory read
>> > >> [nods]
>> > >> you named the bug already
>> > >>
>> > >> "notify" directly comes from userspace struct sigevent::sigev_notify
>> > >> without adult supervision.
>> > >>
>> > >> Reproducer is timer_create + read(/proc/self/timers)
>> > >
>> > > Bah. That's a really old one.
>> > >
>> > > Tentative fix below. That needs more though but looking at the existing
>> > > check there is only one valid combo with SIGEV_THREAD_ID.
>> > >
>> > > Thanks,
>> > >
>> > > tglx
>> > >
>> > > 8<----------------
>> > > --- a/kernel/time/posix-timers.c
>> > > +++ b/kernel/time/posix-timers.c
>> > > @@ -434,6 +434,16 @@ static struct pid *good_sigevent(sigeven
>> > > {
>> > > struct task_struct *rtn = current->group_leader;
>> > >
>> > > + switch (event->sigev_notify) {
>> > > + case SIGEV_NONE:
>> > > + case SIGEV_SIGNAL:
>> > > + case SIGEV_SIGNAL | SIGEV_THREAD_ID:
>> > > + case SIGEV_THREAD:
>> > > + break;
>> > > + default:
>> > > + return NULL;
>> > > + }
>> > > +
>> > > if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
>> > > (!(rtn =
>> > > find_task_by_vpid(event->sigev_notify_thread_id)) ||
>> > > !same_thread_group(rtn, current) ||
>> >
>> > FWIW, this looks correct to me.
>>
>> Did this ever go anywhere? I don't see it in Linus's tree yet...
>
> I learned yesterday that syzboz is understuffed and cannot test patches, so
> I need to find a minute to run the reproducer myself and verify that the
> patch is correct.
Hi Thomas,
Why do you say so? Have you tried to ask it to test?
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
What happened?
