[PATCH][drm-next] drm/amd/display: fix a potential null pointer dereference

[Alex Deucher]

On Thu, Aug 22, 2019 at 3:21 PM Harry Wentland <hwentlan at amd.com> wrote:
>
> On 2019-08-16 6:10 p.m., Colin King wrote:
> > From: Colin Ian King <colin.king at canonical.com>
> >
> > Currently the pointer init_data is dereferenced on the assignment
> > of fw_info before init_data is sanity checked to see if it is null.
> > Fix te potential null pointer dereference on init_data by only
> > performing dereference after it is null checked.
> >
> > Addresses-Coverity: ("Dereference before null check")
> > Fixes: 9adc8050bf3c ("drm/amd/display: make firmware info only load once during dc_bios create")
> > Signed-off-by: Colin Ian King <colin.king at canonical.com>
>
> Reviewed-by: Harry Wentland <harry.wentland at amd.com>
>

Applied.  Thanks!

Alex

> Harry
>
> > ---
> >  drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> > index bee81bf288be..926954c804a6 100644
> > --- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> > +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c
> > @@ -1235,7 +1235,7 @@ static bool calc_pll_max_vco_construct(
> >                       struct calc_pll_clock_source_init_data *init_data)
> >  {
> >       uint32_t i;
> > -     struct dc_firmware_info *fw_info = &init_data->bp->fw_info;
> > +     struct dc_firmware_info *fw_info;
> >       if (calc_pll_cs == NULL ||
> >                       init_data == NULL ||
> >                       init_data->bp == NULL)
> > @@ -1244,6 +1244,7 @@ static bool calc_pll_max_vco_construct(
> >       if (init_data->bp->fw_info_valid)
> >               return false;
> >
> > +     fw_info = &init_data->bp->fw_info;
> >       calc_pll_cs->ctx = init_data->ctx;
> >       calc_pll_cs->ref_freq_khz = fw_info->pll_info.crystal_frequency;
> >       calc_pll_cs->min_vco_khz =
> >
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