On Wed, Jun 18, 2025 at 05:50:16AM +0100, Al Viro wrote:
> NAK. This is not the first time that garbage is suggested and no,
> we are not going to paper over that shite in fs/namei.c.
>
> Not going to happen.
>
> You ARE NOT ALLOWED to call make_bad_inode() on a live inode, period.
> Never, ever to be done.
>
> There's a lot of assertions it violates and there's no chance in
> hell to plaster each with that kind of checks.
>
> Fix NTFS. End of story.
To elaborate a bit: if you look at the end of e.g. their attr_set_size(),
you'll see
out:
if (is_bad) {
bad_inode:
_ntfs_bad_inode(&ni->vfs_inode);
}
return err;
}
This is a bug. So are similar places all over the place there.
You are not supposed to use make_bad_inode() as a general-purpose
"something went wrong, don't wanna see it anymore" tool.
And as long as it stays there, any fuzzing reports of ntfs are pretty
much worthless - any of those places (easily located by grepping for
_ntfs_bad_inode) can fuck the kernel up. Once ntfs folks get around
to saner error recovery, it would make sense to start looking into
fuzzing that thing again. Until then - nope. Again, this is *NOT*
going to be papered over in a random set of places (pretty certain
to remain incomplete) in VFS.
