fs/ntfs3: reject index allocation if $BITMAP is empty but blocks exist

[ Upstream commit 0dc7117da8f92dd5fe077d712a756eccbe377d40 ]

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@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64
Fixes: d99208b91933 ("fs/ntfs3: cancle set bad inode after removing name fails")
Tested-by: syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com
Signed-off-by: Moon Hee Lee <moonhee.lee.ca@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Moon Hee Lee
2025-07-22 10:40:16 -07:00
committed by Greg Kroah-Hartman
parent a86c8b9d03
commit 978aac54e9

View File

@@ -1510,6 +1510,16 @@ 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;
}