From: Ahmed Ehab bottaawesome633@gmail.com
Preventing lockdep_set_subclass from creating a new instance of the string literal. Hence, we will always have the same class->name among parent and subclasses. This prevents kernel panics when looking up a lock class while comparing class locks and class names.
Reported-by: syzbot+7f4a6f7f7051474e40ad@syzkaller.appspotmail.com Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks") Cc: stable@vger.kernel.org Signed-off-by: Ahmed Ehab bottaawesome633@gmail.com --- include/linux/lockdep.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 08b0d1d9d78b..df8fa5929de7 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -173,7 +173,7 @@ static inline void lockdep_init_map(struct lockdep_map *lock, const char *name, (lock)->dep_map.lock_type)
#define lockdep_set_subclass(lock, sub) \ - lockdep_init_map_type(&(lock)->dep_map, #lock, (lock)->dep_map.key, sub,\ + lockdep_init_map_type(&(lock)->dep_map, (lock)->dep_map.name, (lock)->dep_map.key, sub,\ (lock)->dep_map.wait_type_inner, \ (lock)->dep_map.wait_type_outer, \ (lock)->dep_map.lock_type)
From: Ahmed Ehab bottaawesome633@gmail.com
Checking if the lockdep_map->name will change when setting the subclass. It shouldn't change so that the lock class and subclass will have the same name
Reported-by: syzbot+7f4a6f7f7051474e40ad@syzkaller.appspotmail.com Fixes: de8f5e4f2dc1f ("lockdep: Introduce wait-type checks") Cc: stable@vger.kernel.org Signed-off-by: Ahmed Ehab bottaawesome633@gmail.com --- lib/locking-selftest.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index 6f6a5fc85b42..aeed613799ca 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -2710,6 +2710,25 @@ static void local_lock_3B(void)
}
+ /** + * after setting the subclass the lockdep_map.name changes + * if we initialize a new string literal for the subclass + * we will have a new name pointer + */ +static void class_subclass_X1_name_test(void) +{ + printk(" --------------------------------------------------------------------------\n"); + printk(" | class and subclass name test|\n"); + printk(" ---------------------\n"); + const char *name_before_setting_subclass = rwsem_X1.dep_map.name; + const char *name_after_setting_subclass; + + WARN_ON(!rwsem_X1.dep_map.name); + lockdep_set_subclass(&rwsem_X1, 1); + name_after_setting_subclass = rwsem_X1.dep_map.name; + WARN_ON(name_before_setting_subclass != name_after_setting_subclass); +} + static void local_lock_tests(void) { printk(" --------------------------------------------------------------------------\n"); @@ -2916,6 +2935,8 @@ void locking_selftest(void)
local_lock_tests();
+ class_subclass_X1_name_test(); + print_testname("hardirq_unsafe_softirq_safe"); dotest(hardirq_deadlock_softirq_not_deadlock, FAILURE, LOCKTYPE_SPECIAL); pr_cont("\n");
linux-stable-mirror@lists.linaro.org
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botta633