Commit-ID: 4ba053c04aece1f4734056f21b751eee47ea3fb1 Gitweb: http://git.kernel.org/tip/4ba053c04aece1f4734056f21b751eee47ea3fb1 Author: Hitoshi Mitake <mitake@xxxxxxxxxxxxxxxxxxxxx> AuthorDate: Wed, 13 Oct 2010 17:30:26 +0900 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Mon, 18 Oct 2010 18:44:26 +0200 lockdep: Check the depth of subclass Current look_up_lock_class() doesn't check the parameter "subclass". This rarely rises problems because the main caller of this function, register_lock_class(), checks it. But register_lock_class() is not the only function which calls look_up_lock_class(). lock_set_class() and its callees also call it. And lock_set_class() doesn't check this parameter. This will rise problems when the the value of subclass is larger than MAX_LOCKDEP_SUBCLASSES. Because the address (used as the key of class) caliculated with too large subclass has a probability to point another key in different lock_class_key. Of course this problem depends on the memory layout and occurs with really low probability. Signed-off-by: Hitoshi Mitake <mitake@xxxxxxxxxxxxxxxxxxxxx> Cc: Dmitry Torokhov <dtor@xxxxxxx> Cc: Vojtech Pavlik <vojtech@xxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> LKML-Reference: <1286958626-986-1-git-send-email-mitake@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/lockdep.c | 18 ++++++++++-------- 1 files changed, 10 insertions(+), 8 deletions(-) diff --git a/kernel/lockdep.c b/kernel/lockdep.c index bc4d328..42ba65d 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -639,6 +639,16 @@ look_up_lock_class(struct lockdep_map *lock, unsigned int subclass) } #endif + if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { + debug_locks_off(); + printk(KERN_ERR + "BUG: looking up invalid subclass: %u\n", subclass); + printk(KERN_ERR + "turning off the locking correctness validator.\n"); + dump_stack(); + return NULL; + } + /* * Static locks do not have their class-keys yet - for them the key * is the lock object itself: @@ -2745,14 +2755,6 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (DEBUG_LOCKS_WARN_ON(!irqs_disabled())) return 0; - if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) { - debug_locks_off(); - printk("BUG: MAX_LOCKDEP_SUBCLASSES too low!\n"); - printk("turning off the locking correctness validator.\n"); - dump_stack(); - return 0; - } - if (lock->key == &__lockdep_no_validate__) check = 1; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html