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

[Dmitry Vyukov]

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.


-- 
Dmitry Vyukov, Software Engineer, dvyukov@xxxxxxxxxx
Google Germany GmbH, DienerstraÃe 12, 80331, MÃnchen
GeschÃftsfÃhrer: Graham Law, Christine Elizabeth Flores
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
Diese E-Mail ist vertraulich. Wenn Sie nicht der richtige Adressat
sind, leiten Sie diese bitte nicht weiter, informieren Sie den
Absender und lÃschen Sie die E-Mail und alle AnhÃnge. Vielen Dank.
This e-mail is confidential. If you are not the right addressee please
do not forward it, please inform the sender, and please erase this
e-mail including any attachments. Thanks.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/