drm/amd/display: Add 'replay' NULL check in 'edp_set_replay_allow_active()'

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Add 'replay' NULL check in 'edp_set_replay_allow_active()' In the first if statement, we're checking if 'replay' is NULL. But in the second if statement, we're not checking if 'replay' is NULL again before calling replay->funcs->replay_set_power_opt(). if (replay == NULL && force_static) return false; ... if (link->replay_settings.replay_feature_enabled && replay->funcs->replay_set_power_opt) { replay->funcs->replay_set_power_opt(replay, *power_opts, panel_inst); link->replay_settings.replay_power_opt_active = *power_opts; } If 'replay' is NULL, this will cause a null pointer dereference. Fixes the below found by smatch: drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_edp_panel_control.c:895 edp_set_replay_allow_active() error: we previously assumed 'replay' could be null (see line 887)

References

• https://git.kernel.org/stable/c/f610c46771ef1047e46d61807aa7c69cd29e63d8
• https://git.kernel.org/stable/c/e7cadd5d3a8ffe334d0229ba9eda4290138d56e7
• https://git.kernel.org/stable/c/d0e94f4807ff0df66cf447d6b4bbb8ac830e99c3
• https://git.kernel.org/stable/c/f6aed043ee5d75b3d1bfc452b1a9584b63c8f76b