On 2022/10/20 17:14, Gao Xiang wrote:
Hi Chao,
On Thu, Oct 20, 2022 at 04:49:34PM +0800, Chao Yu wrote:
On 2022/10/19 10:21, Gao Xiang wrote:
Hi Yingliang,
On Tue, Oct 18, 2022 at 03:39:47PM +0800, Yang Yingliang wrote:
Inject fault while probing module, kset_register() may fail,
if it fails, but the refcount of kobject is not decreased to
0, the name allocated in kobject_set_name() is leaked. Fix
this by calling kset_put(), so that name can be freed in
callback function kobject_cleanup().
unreferenced object 0xffff888101d228c0 (size 8):
comm "modprobe", pid 276, jiffies 4294722700 (age 13.151s)
hex dump (first 8 bytes):
65 72 6f 66 73 00 ff ff erofs...
backtrace:
[<00000000e2a9a4a6>] __kmalloc_node_track_caller+0x44/0x1b0
[<00000000b8ce02de>] kstrdup+0x3a/0x70
[<000000004a0e01d2>] kstrdup_const+0x63/0x80
[<00000000051b6cda>] kvasprintf_const+0x149/0x180
[<000000004dc51dad>] kobject_set_name_vargs+0x56/0x150
[<00000000b30f0bad>] kobject_set_name+0xab/0xe0
Fixes: 168e9a76200c ("erofs: add sysfs interface")
Signed-off-by: Yang Yingliang <[email protected]>
Thanks for the catch, the issue itself seems true. However, I found
several fses all have this issue.
After I did some discussion with Joseph Qi offline, I'd like to wait
for the conclusion of the following thread:
https://lore.kernel.org/r/[email protected]
Since I tend to think kset_put() should be one fail step of
kset_register().
I guess in error path, it missed to free kobj->name which was allocated by
kobject_set_name(&erofs_root.kobj, "erofs"), so calling kset_put() here looks
fine?
We looked into this yesterday. I think the main problem is that the
kset_put() a reference which is set in kset_init() of kset_register().
Therefore such refernece belongs to an internal implementation and
should not be treated for each kset_register() caller.
Please correct me if I'm wrong here.
Xiang,
Oh, right, I missed reference count operation in kset_put().
Thanks,
Thanks,
Gao Xiang
Thanks,
Thanks,
Gao Xiang
---
fs/erofs/sysfs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
index 783bb7b21b51..653b35001bc5 100644
--- a/fs/erofs/sysfs.c
+++ b/fs/erofs/sysfs.c
@@ -254,8 +254,10 @@ int __init erofs_init_sysfs(void)
kobject_set_name(&erofs_root.kobj, "erofs");
erofs_root.kobj.parent = fs_kobj;
ret = kset_register(&erofs_root);
- if (ret)
+ if (ret) {
+ kset_put(&erofs_root);
goto root_err;
+ }
ret = kobject_init_and_add(&erofs_feat, &erofs_feat_ktype,
NULL, "features");
--
2.25.1
