| From e182bb38d7db7494fa5dcd82da17fe0dedf60ecf Mon Sep 17 00:00:00 2001 |
| From: Tejun Heo <tj@kernel.org> |
| Date: Wed, 20 Feb 2013 15:24:12 -0800 |
| Subject: posix-timer: Don't call idr_find() with out-of-range ID |
| |
| From: Tejun Heo <tj@kernel.org> |
| |
| 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> |
| 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/posix-timers.c | 7 +++++++ |
| 1 file changed, 7 insertions(+) |
| |
| --- a/kernel/posix-timers.c |
| +++ b/kernel/posix-timers.c |
| @@ -639,6 +639,13 @@ static struct k_itimer *__lock_timer(tim |
| { |
| 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) { |
