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| author | Tejun Heo <tj@kernel.org> | 2013-02-20 15:24:12 -0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2013-02-21 17:28:29 +0100 |
| commit | e182bb38d7db7494fa5dcd82da17fe0dedf60ecf (patch) | |
| tree | 5373b72d6bbd6e9b0bda8fae65dd91f3603c3d54 /kernel | |
| parent | 1a13c0b181f218bf56a1a6b8edbaf2876b22314b (diff) | |
| download | linux-e182bb38d7db7494fa5dcd82da17fe0dedf60ecf.tar.bz2 | |
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>
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 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) { |