Re: [PATCH] fs/befs/linuxvfs.c: need signed cast for variable 'block'

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Oct 31, 2013 at 12:08:33PM -0700, Kees Cook wrote:
> On Thu, Oct 31, 2013 at 12:06 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> > On Thu, Oct 31, 2013 at 09:53:59AM -0700, Kees Cook wrote:
> >
> >> If block (type sector_t) is unsigned, we shouldn't cast it signed.
> >> This entire code path should be removed. What is BEFS's expected
> >> maximum block size? (Looks like even befs_blocknr_t is u64, so nothing
> >> seems trivially in danger of wrapping.) I would also note that all the
> >> format strings are wrong too (%ld instead of %lu).
> >
> > FWIW, this
> >         res = befs_fblock2brun(sb, ds, block, &run);
> >         if (res != BEFS_OK) {
> >                 befs_error(sb,
> >                            "<--- befs_get_block() for inode %lu, block "
> >                            "%ld ERROR", inode->i_ino, block);
> >                 return -EFBIG;
> >         }
> > also looks wrong - ioctl(..., FIBMAP, ...) shouldn't be able to spew
> > printks on a valid fs and hitting it with block number greater than
> > file length will, AFAICS, trigger that.
> >
> > I agree that this code needs fixing, but just making gcc STFU about the
> > comparison would only serve to hide the problem.  Anybody familiar with
> > befs or willing to learn it?
> 
> Agreed. MAINTAINERS shows it as orphaned. Perhaps it should be moved
> into staging?

Only if we want to delete the thing.  I'll be glad to take it there, and
remove it in 2 releases and then if anyone complains, we can add it back
easily.  Just let me know.

thanks,

greg k-h