hfsplus: Initialize directory subfolders in hfsplus_mknod

[Siddharth Menon <simeddon@gmail.com>]

    hfsplus: Initialize directory subfolders in hfsplus_mknod
    
    Addresses uninitialized subfolders attribute being used in `hfsplus_subfolders_inc` and `hfsplus_subfolders_dec`.
    
    Fixes: https://syzkaller.appspot.com/bug?extid=fdedff847a0e5e84c39f
    Reported-by: syzbot+fdedff847a0e5e84c39f@syzkaller.appspotmail.com
    Closes: https://syzkaller.appspot.com/x/report.txt?x=16efda06680000

Signed-off-by: Siddharth Menon <simeddon@gmail.com>
---
 fs/hfsplus/btree.c | 1 +
 fs/hfsplus/dir.c   | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/hfsplus/btree.c b/fs/hfsplus/btree.c
index 9e1732a2b92a..13d2e90cb9b1 100644
--- a/fs/hfsplus/btree.c
+++ b/fs/hfsplus/btree.c
@@ -363,6 +363,7 @@ int hfs_bmap_reserve(struct hfs_btree *tree, int rsvd_nodes)
 				HFSPLUS_SB(tree->sb)->alloc_blksz_shift;
 		hip->fs_blocks =
 			hip->alloc_blocks << HFSPLUS_SB(tree->sb)->fs_shift;
+		hip->subfolders = 0;
 		inode_set_bytes(inode, inode->i_size);
 		count = inode->i_size >> tree->node_size_shift;
 		tree->free_nodes += count - tree->node_count;
diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index f5c4b3e31a1c..a4eb287e3d4b 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -485,11 +485,14 @@ static int hfsplus_mknod(struct mnt_idmap *idmap, struct inode *dir,
 
 	mutex_lock(&sbi->vh_mutex);
 	inode = hfsplus_new_inode(dir->i_sb, dir, mode);
+	if (test_bit(HFSPLUS_SB_HFSX, &sbi->flags))
+		HFSPLUS_I(dir)->subfolders = 0;
+
 	if (!inode)
 		goto out;
 
-	if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode))
-		init_special_inode(inode, mode, rdev);
+	if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)){
+		init_special_inode(inode, mode, rdev);}
 
 	res = hfsplus_create_cat(inode->i_ino, dir, &dentry->d_name, inode);
 	if (res)
-- 
2.39.2