hfs: Sanity check the root record

In the syzbot reproducer, the hfs_cat_rec for the root dir has type
HFS_CDR_FIL after being read with hfs_bnode_read() in hfs_super_fill().
This indicates it should be used as an hfs_cat_file, which is 102 bytes.
Only the first 70 bytes of that struct are initialized, however,
because the entrylength passed into hfs_bnode_read() is still the length of
a directory record. This causes uninitialized values to be used later on,
when the hfs_cat_rec union is treated as the larger hfs_cat_file struct.

Add a check to make sure the retrieved record has the correct type
for the root directory (HFS_CDR_DIR), and make sure we load the correct
number of bytes for a directory record.

Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=2db3c7526ba68f4ea776
Tested-by: [email protected]
Tested-by: Leo Stone <[email protected]>
Signed-off-by: Leo Stone <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

0 files changed, 0 insertions, 0 deletions