[PATCH v2 2/2] hfs: Update sanity check of the root record

George Anthony Vernon
2025-11-04T01:49:33Z

syzbot is reporting that BUG() in hfs_write_inode() fires upon unmount
operation when the inode number of the record retrieved as a result of
hfs_cat_find_brec(HFS_ROOT_CNID) is not HFS_ROOT_CNID, for commit
b905bafdea21 ("hfs: Sanity check the root record") checked the record
size and the record type but did not check the inode number.

Reported-by: syzbot+97e301b4b82ae803d21b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=97e301b4b82ae803d21b
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: George Anthony Vernon <contact@gvernon.com>
---
fs/hfs/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/hfs/super.c b/fs/hfs/super.c
index 47f50fa555a4..a7dd20f2d743 100644
--- a/fs/hfs/super.c
+++ b/fs/hfs/super.c
@@ -358,7 +358,7 @@ static int hfs_fill_super(struct super_block *sb, struct fs_context *fc)
goto bail_hfs_find;
}
hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
- if (rec.type != HFS_CDR_DIR)
+ if (rec.type != HFS_CDR_DIR || rec.dir.DirID != cpu_to_be32(HFS_ROOT_CNID))
res = -EIO;
}
if (res)
--
2.50.1