Commit 3d44cc3e authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Linus Torvalds

Null pointer deref with hrtimer_try_to_cancel()

Impact: Prevent kernel crash with posix timer clockid CLOCK_MONOTONIC_RAW

commit 2d42244a (clocksource:
introduce CLOCK_MONOTONIC_RAW) introduced a new clockid, which is only
available to read out the raw not NTP adjusted system time.

The above commit did not prevent that a posix timer can be created
with that clockid. The timer_create() syscall succeeds and initializes
the timer to a non existing hrtimer base. When the timer is deleted
either by timer_delete() or by the exit() cleanup the kernel crashes.

Prevent the creation of timers for CLOCK_MONOTONIC_RAW by setting the
posix clock function to no_timer_create which returns an error code.
Reported-and-tested-by: default avatarEric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ab653872
...@@ -197,6 +197,11 @@ static int common_timer_create(struct k_itimer *new_timer) ...@@ -197,6 +197,11 @@ static int common_timer_create(struct k_itimer *new_timer)
return 0; return 0;
} }
static int no_timer_create(struct k_itimer *new_timer)
{
return -EOPNOTSUPP;
}
/* /*
* Return nonzero if we know a priori this clockid_t value is bogus. * Return nonzero if we know a priori this clockid_t value is bogus.
*/ */
...@@ -248,6 +253,7 @@ static __init int init_posix_timers(void) ...@@ -248,6 +253,7 @@ static __init int init_posix_timers(void)
.clock_getres = hrtimer_get_res, .clock_getres = hrtimer_get_res,
.clock_get = posix_get_monotonic_raw, .clock_get = posix_get_monotonic_raw,
.clock_set = do_posix_clock_nosettime, .clock_set = do_posix_clock_nosettime,
.timer_create = no_timer_create,
}; };
register_posix_clock(CLOCK_REALTIME, &clock_realtime); register_posix_clock(CLOCK_REALTIME, &clock_realtime);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment