Messages in this thread Patch in this message | | | Date | Wed, 20 Feb 2013 14:40:19 -0800 | From | Tejun Heo <> | Subject | [PATCH] posix-timer: don't call idr_find() w/ out-of-range ID |
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When idr_find() is fed a negative ID, it used to look up the ID ignoring the sign bit before recent ("idr: remove MAX_IDR_MASK and move left MAX_IDR_* into idr.c") patch, and triggers WARN_ON_ONCE() after it.
__lock_timer() feeds timer_id from userland directly to idr_find() without sanitizing it which can trigger the above malfunctions. Add a range check on @timer_id before invoking idr_find() in __lock_timer().
While timer_t is defined as int by all archs at the moment, Andrew worries that it may be defined as a larger type later on. Make the test cover larger integers too so that it at least is guaranteed to not return the wrong timer.
Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Sasha Levin <sasha.levin@oracle.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: stable@vger.kernel.org --- kernel/posix-timers.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index b51bb08..6edbb2c 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -637,6 +637,13 @@ static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags) { struct k_itimer *timr; + /* + * timer_t could be any type >= int and we want to make sure any + * @timer_id outside positive int range fails lookup. + */ + if ((unsigned long long)timer_id > INT_MAX) + return NULL; + rcu_read_lock(); timr = idr_find(&posix_timers_id, (int)timer_id); if (timr) {
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