On 11/29/18 10:17 AM, Nicholas Kazlauskas wrote:
> [Why]
> When preferred_mode is NULL a null pointer dereference can occur
> when trying to get the preferred refresh in create_stream_for_sink.
>
> [How]
> Only query preferred_refresh when preferred_mode is not NULL. Consider
> preferred_refresh if it is since it's only being used to compare to
> the previous value.
>
> Fixes: b333730d126e ("drm/amd/display: Fix Scaling (RMX_*) for DC driver")
>
> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
> ---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index ce00e56814ed..478fa810438e 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2848,7 +2848,7 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
> bool native_mode_found = false;
> bool scale = dm_state ? (dm_state->scaling != RMX_OFF) : false;
> int mode_refresh;
> - int preferred_refresh;
> + int preferred_refresh = 0;
>
> struct dc_sink *sink = NULL;
> if (aconnector == NULL) {
> @@ -2907,7 +2907,8 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
> if (!dm_state)
> drm_mode_set_crtcinfo(&mode, 0);
>
> - preferred_refresh = drm_mode_vrefresh(preferred_mode);
> + if (preferred_mode)
> + preferred_refresh = drm_mode_vrefresh(preferred_mode);
>
> /*
> * If scaling is enabled and refresh rate didn't change
>
Actually, this is the same patch as "drm/amd/display: Fix NULL ptr when
calculating refresh rate" from Jerry.
https://patchwork.freedesktop.org/patch/264242/
This can be ignored.
Nicholas Kazlauskas
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