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. -Kees -- Kees Cook Pixel Security