diff options
| author | Tejun Heo <tj@kernel.org> | 2013-02-20 15:24:12 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-03-06 03:24:09 +0000 |
| commit | 4fa1b6edec2f38073f34bb4cd8306e200c3c750c (patch) | |
| tree | 44fc281b4e046a15c774dd5775ba714883a683da /kernel | |
| parent | 7d3cbb434e8a45001d21bfc3ad31738409e9d517 (diff) | |
posix-timer: Don't call idr_find() with out-of-range ID
commit e182bb38d7db7494fa5dcd82da17fe0dedf60ecf upstream.
When idr_find() was 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. Now a negative ID triggers
a WARN_ON_ONCE().
__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.
Note that WARN_ON_ONCE() in idr_find() on id < 0 is transitional
precaution while moving away from ignoring MSB. Once it's gone we can
remove the guard as long as timer_t isn't larger than int.
Signed-off-by: Tejun Heo <tj@kernel.org>nnn
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20130220232412.GL3570@htj.dyndns.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/posix-timers.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c index 69185ae6b701..e885be1e8a11 100644 --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -639,6 +639,13 @@ 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) { |