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authorThomas Gleixner <tglx@linutronix.de>2008-12-20 23:27:34 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2008-12-21 01:13:45 +0300
commit3d44cc3e01ee1b40317f79ed54324e25c4f848df (patch)
tree99feb824dd6beda01bf11c56e412ff147bf24551
parentab65387243f47a7bc11725f733c86bf27248b326 (diff)
downloadlinux-3d44cc3e01ee1b40317f79ed54324e25c4f848df.tar.xz
Null pointer deref with hrtimer_try_to_cancel()
Impact: Prevent kernel crash with posix timer clockid CLOCK_MONOTONIC_RAW commit 2d42244ae71d6c7b0884b5664cf2eda30fb2ae68 (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>
-rw-r--r--kernel/posix-timers.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 5e79c662294b..a140e44eebba 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -197,6 +197,11 @@ static int common_timer_create(struct k_itimer *new_timer)
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.
*/
@@ -248,6 +253,7 @@ static __init int init_posix_timers(void)
.clock_getres = hrtimer_get_res,
.clock_get = posix_get_monotonic_raw,
.clock_set = do_posix_clock_nosettime,
+ .timer_create = no_timer_create,
};
register_posix_clock(CLOCK_REALTIME, &clock_realtime);