Hi Pavel,
On Thu, Aug 15, 2019 at 09:01:32AM +0200, Pavel Machek wrote:
> Hi!
>
> > > > + /*
> > > > + * on-disk error, let's only BUG_ON in the debugging mode.
> > > > + * otherwise, it will return 1 to just skip the invalid name
> > > > + * and go on (in consideration of the lookup performance).
> > > > + */
> > > > + DBG_BUGON(qd->name > qd->end);
> > >
> > > I believe you should check for errors in non-debug mode, too.
> >
> > Thanks for your kindly reply!
> >
> > The following is just my personal thought... If I am wrong, please
> > kindly point out...
> >
> > As you can see, this is a new prefixed string binary search algorithm
> > which can provide similar performance with hashed approach (but no
> > need to store hash value at all), so I really care about its lookup
> > performance.
> >
> > There is something needing to be concerned, is, whether namei() should
> > report any potential on-disk issues or just return -ENOENT for these
> > corrupted dirs, I think I tend to use the latter one.
>
> -ENOENT is okay for corrupted directories, as long as corrupted
> directories do not cause some kind of security bugs (memory
> corruption, crashes, ...)
Yes, I am certain that it will return -ENOENT for such corrupted
directories and it will certainly not crash the kernel as well.
I have fuzzed it for several months and it seems fine after
commit 419d6efc50e9 ("staging: erofs: keep corrupted fs from crashing kernel in erofs_namei()")
Don't worry about that :)
Thanks,
Gao Xiang
>
>
> Best regards,
> Pavel
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