[PATCH 6.6.y 2/2] btrfs: fix double free in create_space_info_sub_group() error path

[Sasha Levin <sashal@kernel.org>]

From: Guangshuo Li <lgs201920130244@gmail.com>

[ Upstream commit a7449edf96143f192606ec8647e3167e1ecbd728 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/space-info.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 292789a1b84b9..8fe35fd82912e 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -263,10 +263,8 @@ 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;
 }
 
-- 
2.53.0