Re: [PATCH] ntfs: Ensure $Extend is a directory

[Greg KH]

On Sun, Jul 24, 2022 at 08:34:48AM -0700, Soumya Negi wrote:
> On Sun, Jul 24, 2022 at 03:47:01PM +0200, Greg KH wrote:
> > On Sun, Jul 24, 2022 at 06:21:07AM -0700, Soumya Negi wrote:
> > > Fixes Syzbot bug: kernel BUG in ntfs_lookup_inode_by_name
> > > https://syzkaller.appspot.com/bug?id=32cf53b48c1846ffc25a185a2e92e170d1a95d71
> > > 
> > > Check whether $Extend is a directory or not( for NTFS3.0+) while loading
> > > system files. If it isn't(as in the case of this bug where the mft record for
> > > $Extend contains a regular file), load_system_files() returns false.
> > 
> > Please wrap your changelog text at 72 columns like your editor asked you
> > to when writing this :)
> 
> I will correct the changelog(Don't think I can wrap the bug report
> link. Checkpatch will still give a warning. Is that okay?).

Yes, do not wrap links.

> > > Reported-by: syzbot+30b7f850c6d98ea461d2@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: Soumya Negi <soumya.negi97@xxxxxxxxx>
> > 
> > What commit caused this problem?  What Fixes: tag should go here?
> 
> I don't think this was caused by any specific commit.The $Extend
> directory check is not present in any previous releases. Syzbot has
> also not been able to produce a cause bisection for the bug. So no fixes
> tag(please correct me if I am wrong).
> 
> > Should it go to stable kernels?  If so, how far back?
> 
> Since the NTFS extension file was new to NTFS 3.0, perhaps the patch 
> should apply all the way back to the first release with NTFS3.0 support?

Yes, mark it there.

thanks,

greg k-h