[PATCH v4 1/2] locking/lockdep: Forcing subclasses to have same name pointer as their parent class
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)
On Mon, Jul 15, 2024 at 09:34:46AM +0300, botta633 wrote:
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(-)
Hi,
This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him a patch that has triggered this response. He used to manually respond to these common problems, but in order to save his sanity (he kept writing the same thing over and over, yet to different people), I was created. Hopefully you will not take offence and will fix the problem in your patch and resubmit it so that it can be accepted into the Linux kernel tree.
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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 -
Greg KH