[PATCH] hfsplus: fix uninit-value in hfsplus_delete_cat()

[ChenXiaoSong]

Syzkaller reported BUG as follows:

  =====================================================
  BUG: KMSAN: uninit-value in hfsplus_subfolders_dec
                              fs/hfsplus/catalog.c:248 [inline]
  BUG: KMSAN: uninit-value in hfsplus_delete_cat+0x1207/0x14d0
                              fs/hfsplus/catalog.c:419
   hfsplus_subfolders_dec fs/hfsplus/catalog.c:248 [inline]
   hfsplus_delete_cat+0x1207/0x14d0 fs/hfsplus/catalog.c:419
   hfsplus_rmdir+0x141/0x3d0 fs/hfsplus/dir.c:425
   hfsplus_rename+0x102/0x2e0 fs/hfsplus/dir.c:545
   vfs_rename+0x1e4c/0x2800 fs/namei.c:4779
   do_renameat2+0x173d/0x1dc0 fs/namei.c:4930
   __do_sys_renameat2 fs/namei.c:4963 [inline]
   __se_sys_renameat2 fs/namei.c:4960 [inline]
   __ia32_sys_renameat2+0x14b/0x1f0 fs/namei.c:4960
   do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
   __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
   do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
   do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
   entry_SYSENTER_compat_after_hwframe+0x70/0x82

  Uninit was stored to memory at:
   hfsplus_subfolders_inc fs/hfsplus/catalog.c:232 [inline]
   hfsplus_create_cat+0x19e3/0x19f0 fs/hfsplus/catalog.c:314
   hfsplus_mknod+0x1fd/0x560 fs/hfsplus/dir.c:494
   hfsplus_mkdir+0x54/0x60 fs/hfsplus/dir.c:529
   vfs_mkdir+0x62a/0x870 fs/namei.c:4036
   do_mkdirat+0x466/0x7b0 fs/namei.c:4061
   __do_sys_mkdirat fs/namei.c:4076 [inline]
   __se_sys_mkdirat fs/namei.c:4074 [inline]
   __ia32_sys_mkdirat+0xc4/0x120 fs/namei.c:4074
   do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
   __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
   do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
   do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
   entry_SYSENTER_compat_after_hwframe+0x70/0x82

  Uninit was created at:
   __alloc_pages+0x9f1/0xe80 mm/page_alloc.c:5581
   alloc_pages+0xaae/0xd80 mm/mempolicy.c:2285
   alloc_slab_page mm/slub.c:1794 [inline]
   allocate_slab+0x1b5/0x1010 mm/slub.c:1939
   new_slab mm/slub.c:1992 [inline]
   ___slab_alloc+0x10c3/0x2d60 mm/slub.c:3180
   __slab_alloc mm/slub.c:3279 [inline]
   slab_alloc_node mm/slub.c:3364 [inline]
   slab_alloc mm/slub.c:3406 [inline]
   __kmem_cache_alloc_lru mm/slub.c:3413 [inline]
   kmem_cache_alloc_lru+0x6f3/0xb30 mm/slub.c:3429
   alloc_inode_sb include/linux/fs.h:3125 [inline]
   hfsplus_alloc_inode+0x56/0xc0 fs/hfsplus/super.c:627
   alloc_inode+0x83/0x440 fs/inode.c:259
   iget_locked+0x2a1/0xe20 fs/inode.c:1286
   hfsplus_iget+0x5f/0xb60 fs/hfsplus/super.c:64
   hfsplus_btree_open+0x13b/0x1cf0 fs/hfsplus/btree.c:150
   hfsplus_fill_super+0x12b0/0x2a80 fs/hfsplus/super.c:473
   mount_bdev+0x508/0x840 fs/super.c:1401
   hfsplus_mount+0x49/0x60 fs/hfsplus/super.c:641
   legacy_get_tree+0x10c/0x280 fs/fs_context.c:610
   vfs_get_tree+0xa1/0x500 fs/super.c:1531
   do_new_mount+0x694/0x1580 fs/namespace.c:3040
   path_mount+0x71a/0x1eb0 fs/namespace.c:3370
   do_mount fs/namespace.c:3383 [inline]
   __do_sys_mount fs/namespace.c:3591 [inline]
   __se_sys_mount+0x734/0x840 fs/namespace.c:3568
   __ia32_sys_mount+0xdf/0x140 fs/namespace.c:3568
   do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
   __do_fast_syscall_32+0xa2/0x100 arch/x86/entry/common.c:178
   do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
   do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:246
   entry_SYSENTER_compat_after_hwframe+0x70/0x82
  =====================================================

Fix this by initializing 'subfolders' of 'struct hfsplus_inode_info'
in hfsplus_iget().

Link: https://syzkaller.appspot.com/bug?id=981f82f21b973f2f5663dfea581ff8cee1ddfef2
Signed-off-by: ChenXiaoSong <chenxiaosong2@xxxxxxxxxx>
---
 fs/hfsplus/super.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index 122ed89ebf9f..612c07857667 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -72,6 +72,7 @@ struct inode *hfsplus_iget(struct super_block *sb, unsigned long ino)
 	mutex_init(&HFSPLUS_I(inode)->extents_lock);
 	HFSPLUS_I(inode)->flags = 0;
 	HFSPLUS_I(inode)->extent_state = 0;
+	HFSPLUS_I(inode)->subfolders = 0;
 	HFSPLUS_I(inode)->rsrc_inode = NULL;
 	atomic_set(&HFSPLUS_I(inode)->opencnt, 0);
 
-- 
2.31.1