Re: [PATCH v2] tty: fix data race in flush_to_ldisc

[Greg KH]

On Thu, Sep 17, 2015 at 03:21:02PM +0200, Dmitry Vyukov wrote:
> On Thu, Sep 17, 2015 at 3:18 PM, Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> wrote:
> > On Thu, Sep 17, 2015 at 8:53 AM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >> On Thu, Sep 17, 2015 at 12:39:36PM +0200, Dmitry Vyukov wrote:
> >>> flush_to_ldisc reads port->itty and checks that it is not NULL,
> >>> concurrently release_tty sets port->itty to NULL. It is possible
> >>> that flush_to_ldisc loads port->itty once, ensures that it is
> >>> not NULL, but then reloads it again and uses. The second load
> >>> can already return NULL, which will cause a crash.
> >>>
> >>> Use READ_ONCE to read port->itty.
> >>>
> >>> The data race was found with KernelThreadSanitizer (KTSAN).
> >>>
> >>> Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> >>
> >> You sent 3 patches here, but no hint as to what order they need to be
> >> applied in.  Please resend them as a patch series (i.e. 1/3, 2/3, 3/3)
> >> so they can be applied correctly.
> >
> > Greg,
> >
> > I don't think these 3 patches are dependent on each other; I think they
> > can be applied in any order.
> 
> 
> Yes, these patches are independent and can be applied in any order,
> and any subset of them can be applied.
> I can send them as patch series if necessary, though.

Please do, that makes it easier for me.

thanks,

greg k-h
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