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authorTejun Heo <tj@kernel.org>2013-02-20 15:24:12 -0800
committerThomas Gleixner <tglx@linutronix.de>2013-02-21 17:28:29 +0100
commite182bb38d7db7494fa5dcd82da17fe0dedf60ecf (patch)
tree5373b72d6bbd6e9b0bda8fae65dd91f3603c3d54
parent1a13c0b181f218bf56a1a6b8edbaf2876b22314b (diff)
posix-timer: Don't call idr_find() with out-of-range ID
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> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20130220232412.GL3570@htj.dyndns.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--kernel/posix-timers.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 10349d5f2ec3..7edfe4b901e7 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) {