Re: [PATCH] erofs: move erofs out of staging

[Eric Biggers]

On Sun, Aug 18, 2019 at 08:58:12AM -0700, Christoph Hellwig wrote:
> On Sun, Aug 18, 2019 at 11:11:54AM -0400, Theodore Y. Ts'o wrote:
> > Note that of the mainstream file systems, ext4 and xfs don't guarantee
> > that it's safe to blindly take maliciously provided file systems, such
> > as those provided by a untrusted container, and mount it on a file
> > system without problems.  As I recall, one of the XFS developers
> > described file system fuzzing reports as a denial of service attack on
> > the developers.
> 
> I think this greatly misrepresents the general attitute of the XFS
> developers.  We take sanity checks for the modern v5 on disk format
> very series, and put a lot of effort into handling corrupted file
> systems as good as possible, although there are of course no guaranteeÑ.
> 
> The quote that you've taken out of context is for the legacy v4 format
> that has no checksums and other integrity features.

Ted's observation was about maliciously-crafted filesystems, though, so
integrity-only features such as metadata checksums are irrelevant.  Also the
filesystem version is irrelevant; anything accepted by the kernel code (even if
it's legacy/deprecated) is open attack surface.

I personally consider it *mandatory* that we deal with this stuff.  But I can
understand that we don't do a good job at it, so we shouldn't hold a new
filesystem to an unfairly high standard relative to other filesystems...

- Eric