Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
authorLinus Torvalds <torvalds@linux-foundation.org>
Sun, 17 Dec 2017 21:48:50 +0000 (13:48 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 17 Dec 2017 21:48:50 +0000 (13:48 -0800)
Pull timer fix from Thomas Gleixner:
 "A single bugfix which prevents arbitrary sigev_notify values in
  posix-timers"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  posix-timer: Properly check sigevent->sigev_notify

kernel/time/posix-timers.c

index 13d6881f908b7f91a5669264a060f59d7990f801..ec999f32c84058a0624d55ff3ee26a4fac63eb57 100644 (file)
@@ -434,17 +434,22 @@ static struct pid *good_sigevent(sigevent_t * event)
 {
        struct task_struct *rtn = current->group_leader;
 
-       if ((event->sigev_notify & SIGEV_THREAD_ID ) &&
-               (!(rtn = find_task_by_vpid(event->sigev_notify_thread_id)) ||
-                !same_thread_group(rtn, current) ||
-                (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL))
+       switch (event->sigev_notify) {
+       case SIGEV_SIGNAL | SIGEV_THREAD_ID:
+               rtn = find_task_by_vpid(event->sigev_notify_thread_id);
+               if (!rtn || !same_thread_group(rtn, current))
+                       return NULL;
+               /* FALLTHRU */
+       case SIGEV_SIGNAL:
+       case SIGEV_THREAD:
+               if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX)
+                       return NULL;
+               /* FALLTHRU */
+       case SIGEV_NONE:
+               return task_pid(rtn);
+       default:
                return NULL;
-
-       if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) &&
-           ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX)))
-               return NULL;
-
-       return task_pid(rtn);
+       }
 }
 
 static struct k_itimer * alloc_posix_timer(void)
@@ -669,7 +674,7 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting)
        struct timespec64 ts64;
        bool sig_none;
 
-       sig_none = (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE;
+       sig_none = timr->it_sigev_notify == SIGEV_NONE;
        iv = timr->it_interval;
 
        /* interval timer ? */
@@ -856,7 +861,7 @@ int common_timer_set(struct k_itimer *timr, int flags,
 
        timr->it_interval = timespec64_to_ktime(new_setting->it_interval);
        expires = timespec64_to_ktime(new_setting->it_value);
-       sigev_none = (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE;
+       sigev_none = timr->it_sigev_notify == SIGEV_NONE;
 
        kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none);
        timr->it_active = !sigev_none;