ubifs: dbg_check_idx_size: Fix kmemleak if loading znode failed

If function dbg_check_idx_size() failed by loading znode in mounting
process, there are two problems:
  1. Allocated znodes won't be freed, which causes kmemleak in kernel:
     ubifs_mount
      dbg_check_idx_size
       dbg_walk_index
        c->zroot.znode = ubifs_load_znode
	child = ubifs_load_znode // failed
	// Loaded znodes won't be freed in error handling path.
  2. Global variable ubifs_clean_zn_cnt is not decreased, because
     ubifs_tnc_close() is not invoked in error handling path, which
     triggers a warning in ubifs_exit():
      WARNING: CPU: 1 PID: 1576 at fs/ubifs/super.c:2486 ubifs_exit
      Modules linked in: zstd ubifs(-) ubi nandsim
      CPU: 1 PID: 1576 Comm: rmmod Not tainted 6.7.0-rc6
      Call Trace:
	ubifs_exit+0xca/0xc70 [ubifs]
	__do_sys_delete_module+0x29a/0x4a0
	do_syscall_64+0x6f/0x140

Fix it by adding error handling path in dbg_check_idx_size() to release
tnc tree.

Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Suggested-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 3916dc4f30ca..6eba287ae66c 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1903,6 +1903,7 @@ struct ubifs_znode *ubifs_tnc_postorder_next(const struct ubifs_info *c,
 					     struct ubifs_znode *znode);
 long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
 			       struct ubifs_znode *zr);
+void ubifs_destroy_tnc_tree(struct ubifs_info *c);
 struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
 				     struct ubifs_zbranch *zbr,
 				     struct ubifs_znode *parent, int iip);