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Null pointer deref with hrtimer_try_to_cancel() 

Impact: Prevent kernel crash with posix timer clockid CLOCK_MONOTONIC_RAW

commit 2d42244ae7 (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: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Thomas Gleixner 2008-12-20 21:27:34 +01:00 committed by Linus Torvalds
parent ab65387243
commit 3d44cc3e01
1 changed files with 6 additions and 0 deletions
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6
kernel/posix-timers.c
View File

@ -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)
.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);