[PATCH 2/2] drm/dp: Don't trust drm_dp_downstream_id()

[Jani Nikula]

On Fri, 21 Jul 2017, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> Quoting Jani Nikula (2017-07-21 08:22:27)
>> On Thu, 20 Jul 2017, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>> > Before we interpret drm_dp_downstream_id() as a string, make sure it is
>> > NULL terminated, even when drm_dp_downtsream_id() fails.
>> >
>> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101660
>> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> > ---
>> >  drivers/gpu/drm/drm_dp_helper.c | 3 ++-
>> >  1 file changed, 2 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
>> > index 1d9e30f0dbf8..08af8d6b844b 100644
>> > --- a/drivers/gpu/drm/drm_dp_helper.c
>> > +++ b/drivers/gpu/drm/drm_dp_helper.c
>> > @@ -544,7 +544,7 @@ void drm_dp_downstream_debug(struct seq_file *m,
>> >                                DP_DETAILED_CAP_INFO_AVAILABLE;
>> >       int clk;
>> >       int bpc;
>> > -     char id[6];
>> > +     char id[7];
>> >       int len;
>> >       uint8_t rev[2];
>> >       int type = port_cap[0] & DP_DS_PORT_TYPE_MASK;
>> > @@ -583,6 +583,7 @@ void drm_dp_downstream_debug(struct seq_file *m,
>> >               seq_puts(m, "        Type: N/A\n");
>> >       }
>> >  
>> > +     memset(id, 0, sizeof(id));
>> >       drm_dp_downstream_id(aux, id);
>> >       seq_printf(m, "        ID: %s\n", id);
>> 
>> Reviewed-by: Jani Nikula <jani.nikula at intel.com>
>> 
>> although I'd probably have gone for checking the return value of
>> drm_dp_downstream_id() and using %*pE format with strnlen for the
>> length.
>
> I'm also wondering if we should treat it as a string? Print hexadecimal
> + ascii? There's probably a printf specifier for that as well.

Missed your mail, pushed already. The rest is for another patch, another
day.

BR,
Jani.


-- 
Jani Nikula, Intel Open Source Technology Center