Messages in this thread Patch in this message | | | Date | Wed, 20 Feb 2013 13:01:16 -0800 | From | Tejun Heo <> | Subject | [PATCH] posix-timer: don't call idr_find() w/ negative ID |
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Recent idr updates make idr_find() trigger WARN_ON_ONCE() before returning NULL when a negative ID is specified. Apparently, posix-timer::__lock_timer() was depending on idr_find() returning NULL on negative ID, thus triggering the new WARN_ON_ONCE(). Make __lock_timer() first check whether @timer_id is negative and return NULL without invoking idr_find() if so.
Note that the previous code was theoretically broken. idr_find() masked off the sign bit before performing lookup and if the matching IDs were in use, it would have returned pointer for the incorrect entry.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> --- Sasha, can you please test whether this makes the warning go away?
Thanks.
kernel/posix-timers.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index b51bb08..92465f9 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -637,6 +637,9 @@ static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags) { struct k_itimer *timr; + if ((int)timer_id < 0) + return NULL; + rcu_read_lock(); timr = idr_find(&posix_timers_id, (int)timer_id); if (timr) {
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