Re: [PATCH 4.4 17/25] USB: serial: digi_acceleport: fix OOB data sanity check

Johan Hovold
2017-02-24T18:13:57Z

On Fri, Feb 24, 2017 at 06:55:02PM +0100, Greg Kroah-Hartman wrote:
> On Fri, Feb 24, 2017 at 06:33:04PM +0100, Johan Hovold wrote:
> > On Fri, Feb 24, 2017 at 01:38:25PM +0000, Ben Hutchings wrote: > On Fri, 2017-02-24 at 09:25 +0100, Greg Kroah-Hartman wrote:
> > > > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > > >
> > > > ------------------
> > > >
> > > > From: Johan Hovold <johan@kernel.org>
> > > >
> > > > commit 2d380889215fe20b8523345649dee0579821800c upstream.
> > > >
> > > > Make sure to check for short transfers to avoid underflow in a loop
> > > > condition when parsing the receive buffer.
> > > >
> > > > Also fix an off-by-one error in the incomplete sanity check which could
> > > > lead to invalid data being parsed.
> > >
> > > This appears to *introduce* an off-by-one. Which is not as serious as
> > > the underflow, but is still a regression.

> > Good catch, thanks! The original loop condition was indeed correct
> > (modulo the missing underflow check), and I'll post a follow-up fix to
> > address this.

> > You should probably not apply this one until after the follow-up is in
> > Linus' tree as this patch breaks TIOCMGET.
>
> Ok, I'll drop this one from the stable tree now. Remind me to pick this
> one up when the fixup hits Linus's tree.

Thanks, will do.

Johan