Index allocation requires at least one bit in the $BITMAP attribute to track usage of index entries. If the bitmap is empty while index blocks are already present, this reflects on-disk corruption. syzbot triggered this condition using a malformed NTFS image. During a rename() operation involving a long filename (which spans multiple index entries), the empty bitmap allowed the name to be added without valid tracking. Subsequent deletion of the original entry failed with -ENOENT, due to unexpected index state. Reject such cases by verifying that the bitmap is not empty when index blocks exist. Reported-by: syzbot+b0373017f711c06ada64@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64 Fixes: d99208b91933 ("fs/ntfs3: cancle set bad inode after removing name fails") Tested-by: syzbot+b0373017f711c06ada64@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Moon Hee Lee <moonhee.lee.ca@xxxxxxxxx> --- fs/ntfs3/index.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c index 1bf2a6593dec..6d1bf890929d 100644 --- a/fs/ntfs3/index.c +++ b/fs/ntfs3/index.c @@ -1508,6 +1508,16 @@ static int indx_add_allocate(struct ntfs_index *indx, struct ntfs_inode *ni, bmp_size = bmp_size_v = le32_to_cpu(bmp->res.data_size); } + /* + * Index blocks exist, but $BITMAP has zero valid bits. + * This implies an on-disk corruption and must be rejected. + */ + if (in->name == I30_NAME && + unlikely(bmp_size_v == 0 && indx->alloc_run.count)) { + err = -EINVAL; + goto out1; + } + bit = bmp_size << 3; } -- 2.43.0
