Re: [PATCH] isofs: fix timestamps beyond 2027

[Anders Larsen <al@alarsen.net>]

On Thursday, 19 October 2017 12:51:05 CEST Al Viro wrote:
> On Thu, Oct 19, 2017 at 11:50:18AM +0200, Arnd Bergmann wrote:
> > isofs uses a 'char' variable to load the number of years since
> > 1900 for an inode timestamp. On architectures that use a signed
> > char type by default, this results in an invalid date for
> > anything beyond 2027.
> > 
> > This adds a cast to 'u8' for the year number, which should extend
> > the shelf life of the file system until 2155.
> > 
> > This should be backported to all kernels that might still be
> > in use by that date.
> > 
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> > 
> >  fs/isofs/util.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/isofs/util.c b/fs/isofs/util.c
> > index 005a15cfd30a..f40796c4c6c2 100644
> > --- a/fs/isofs/util.c
> > +++ b/fs/isofs/util.c
> > @@ -20,7 +20,7 @@ int iso_date(char * p, int flag)
> > 
> >  	int year, month, day, hour, minute, second, tz;
> >  	int crtime;
> > 
> > -	year = p[0];
> > +	year = (int)(u8)p[0];
> 
> This is BS; just turn that
>         char time[7];
> in struct stamp into
> 	unsigned char time[7];
> and adjust iso_date() accordingly.  Or make that
> sucker actually take struct stamp *, while we are at it.
> 
> And I'd suggest going through the rest of on-disk structures in
> rock.h and looking for other trouble of that sort.

There are more candidates in include/uapi/linux/iso_fs.h - most of them seems 
to be unused (by us), but at the very least struct iso_directory_record 
contains a date-field of the same sort that is indeed used.

Cheers
Anders