This is a note to let you know that I've just added the patch titled class: fix possible memory leak in __class_register() to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: class-fix-possible-memory-leak-in-__class_register.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 31886254b3a96fac4a3017c8ba2bc94e309ec6de Author: Yang Yingliang <yangyingliang@xxxxxxxxxx> Date: Wed Oct 26 16:28:03 2022 +0800 class: fix possible memory leak in __class_register() [ Upstream commit 8c3e8a6bdb5253b97ad532570f8b5db5f7a06407 ] If class_add_groups() returns error, the 'cp->subsys' need be unregister, and the 'cp' need be freed. We can not call kset_unregister() here, because the 'cls' will be freed in callback function class_release() and it's also freed in caller's error path, it will cause double free. So fix this by calling kobject_del() and kfree_const(name) to cleanup kobject. Besides, call kfree() to free the 'cp'. Fault injection test can trigger this: unreferenced object 0xffff888102fa8190 (size 8): comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s) hex dump (first 8 bytes): 70 6b 74 63 64 76 64 00 pktcdvd. backtrace: [<00000000e7c7703d>] __kmalloc_track_caller+0x1ae/0x320 [<000000005e4d70bc>] kstrdup+0x3a/0x70 [<00000000c2e5e85a>] kstrdup_const+0x68/0x80 [<000000000049a8c7>] kvasprintf_const+0x10b/0x190 [<0000000029123163>] kobject_set_name_vargs+0x56/0x150 [<00000000747219c9>] kobject_set_name+0xab/0xe0 [<0000000005f1ea4e>] __class_register+0x15c/0x49a unreferenced object 0xffff888037274000 (size 1024): comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s) hex dump (first 32 bytes): 00 40 27 37 80 88 ff ff 00 40 27 37 80 88 ff ff .@'7.....@'7.... 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... backtrace: [<00000000151f9600>] kmem_cache_alloc_trace+0x17c/0x2f0 [<00000000ecf3dd95>] __class_register+0x86/0x49a Fixes: ced6473e7486 ("driver core: class: add class_groups support") Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221026082803.3458760-1-yangyingliang@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/base/class.c b/drivers/base/class.c index d8a6a5864c2e..61784503ca40 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -191,6 +191,11 @@ int __class_register(struct class *cls, struct lock_class_key *key) } error = class_add_groups(class_get(cls), cls->class_groups); class_put(cls); + if (error) { + kobject_del(&cp->subsys.kobj); + kfree_const(cp->subsys.kobj.name); + kfree(cp); + } return error; } EXPORT_SYMBOL_GPL(__class_register);