RE: [PATCH] time: Avoid undefined behaviour in timespec64_to_ns

[Zengtao (B)]

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@xxxxxxxx]
> Sent: Tuesday, September 15, 2020 8:45 PM
> To: Zengtao (B)
> Cc: Thomas Gleixner; Vincenzo Frascino; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] time: Avoid undefined behaviour in
> timespec64_to_ns
> 
> On Tue, Sep 15, 2020 at 2:20 PM Zengtao (B)
> <prime.zeng@xxxxxxxxxxxxx> wrote:
> 
> > > > Fixes: bd40a175769d ("y2038: itimer: change implementation to
> > > timespec64")
> > >
> > > This one caused the regression, but if we add the check here, it
> > > may be best to also add it in prior kernels that may have the same
> > > bug in other callers of the same function. Maybe backport all the
> > > way to stable kernels that first added timespec64?
> > >
> >
> > I think we need to do the backport, but not sure about the start
> point
> > Thanks for your review.
> 
> I would suggest
> 
> Cc: <stable@xxxxxxxxxxxxxxx> # v3.17+
> Fixes: 361a3bf00582 ("time64: Add time64.h header and define
> struct timespec64")

Yes, make sense, commit 361a3bf00582 introduce a potential issue and
 commit bd40a175769d trigger the issue.

Regards
Zengtao 

> 
>        Arnd