btrfs: fix double free in create_space_info_sub_group() error path

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@vger.kernel.org # 6.18+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index e017bb182c8cd196e75a226b44f18963ec4e40dc..8278e7998bc9a0b8848cd53f4b445ab6faef27e1 100644 (file)
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -287,10 +287,8 @@ static int create_space_info_sub_group(struct btrfs_space_info *parent, u64 flag
        sub_group->subgroup_id = id;
 
        ret = btrfs_sysfs_add_space_info_type(sub_group);
-       if (ret) {
-               kfree(sub_group);
+       if (ret)
                parent->sub_group[index] = NULL;
-       }
        return ret;
 }