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). Reported-by: syzbot+2db3c7526ba68f4ea776@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=2db3c7526ba68f4ea776 Tested-by: syzbot+2db3c7526ba68f4ea776@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Leo Stone <leocstone@xxxxxxxxx> --- fs/hfs/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/hfs/super.c b/fs/hfs/super.c index 3bee9b5dba5e..02d78992eefd 100644 --- a/fs/hfs/super.c +++ b/fs/hfs/super.c @@ -354,6 +354,8 @@ 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) + res = -EIO; } if (res) goto bail_hfs_find; -- 2.43.0
