[PATCH] btrfs: fix double free in create_space_info_sub_group() error path

[Guangshuo Li]

When kobject_init_and_add() fails, the call chain is:

create_space_info_sub_group()
-> btrfs_sysfs_add_space_info_type()
-> kobject_init_and_add()
-> failure
-> kobject_put(&sub_group->kobj)
-> space_info_release()
-> kfree(sub_group)

Then control returns to create_space_info_sub_group(), where:

btrfs_sysfs_add_space_info_type() returns error
-> kfree(sub_group)

Thus, sub_group is freed twice.

Keep parent->sub_group[index] = NULL for the failure path, but after
btrfs_sysfs_add_space_info_type() has called kobject_put(), let the
kobject release callback handle the cleanup.

Fixes: f92ee31e031c ("btrfs: introduce btrfs_space_info sub-group")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Guangshuo Li <lgs201920130244@xxxxxxxxx>
---
 fs/btrfs/space-info.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index d7176eb2fcbf..f5d0f587b755 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -277,7 +277,6 @@ static int create_space_info_sub_group(struct btrfs_space_info *parent, u64 flag
 
 	ret = btrfs_sysfs_add_space_info_type(sub_group);
 	if (ret) {
-		kfree(sub_group);
 		parent->sub_group[index] = NULL;
 	}
 	return ret;
-- 
2.43.0