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, 8 deletions

diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index f4728e65d1bd..45cacdcd4746 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -3116,14 +3116,7 @@ static void tnc_destroy_cnext(struct ubifs_info *c)
 void ubifs_tnc_close(struct ubifs_info *c)
 {
 	tnc_destroy_cnext(c);
-	if (c->zroot.znode) {
-		long n, freed;
-
-		n = atomic_long_read(&c->clean_zn_cnt);
-		freed = ubifs_destroy_tnc_subtree(c, c->zroot.znode);
-		ubifs_assert(c, freed == n);
-		atomic_long_sub(n, &ubifs_clean_zn_cnt);
-	}
+	ubifs_destroy_tnc_tree(c);
 	kfree(c->gap_lebs);
 	kfree(c->ilebs);
 	destroy_old_idx(c);