drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_han...

This commit adds a null check for the 'afb' variable in the
amdgpu_dm_plane_handle_cursor_update function. Previously, 'afb' was
assumed to be null, but was used later in the code without a null check.
This could potentially lead to a null pointer dereference.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_plane.c:1298 amdgpu_dm_plane_handle_cursor_update() error: we previously assumed 'afb' could be null (see line 1252)

Cc: Tom Chung <chiahsuan.chung@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Roman Li <roman.li@amd.com>
Cc: Hersen Wu <hersenxs.wu@amd.com>
Cc: Alex Hung <alex.hung@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Cc: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
index a64f20fcddaa05dd8df5049f97ca056115d81be6..b339642b86c097d5f59a9ab7d54ecb35ee17c1a4 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
@@ -1246,14 +1246,22 @@ void amdgpu_dm_plane_handle_cursor_update(struct drm_plane *plane,
 {
        struct amdgpu_device *adev = drm_to_adev(plane->dev);
        struct amdgpu_framebuffer *afb = to_amdgpu_framebuffer(plane->state->fb);
-       struct drm_crtc *crtc = afb ? plane->state->crtc : old_plane_state->crtc;
-       struct dm_crtc_state *crtc_state = crtc ? to_dm_crtc_state(crtc->state) : NULL;
-       struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
-       uint64_t address = afb ? afb->address : 0;
+       struct drm_crtc *crtc;
+       struct dm_crtc_state *crtc_state;
+       struct amdgpu_crtc *amdgpu_crtc;
+       u64 address;
        struct dc_cursor_position position = {0};
        struct dc_cursor_attributes attributes;
        int ret;
 
+       if (!afb)
+               return;
+
+       crtc = plane->state->crtc ? plane->state->crtc : old_plane_state->crtc;
+       crtc_state = crtc ? to_dm_crtc_state(crtc->state) : NULL;
+       amdgpu_crtc = to_amdgpu_crtc(crtc);
+       address = afb->address;
+
        if (!plane->state->fb && !old_plane_state->fb)
                return;