2021-12-16 18:14:56

by José Expósito

Subject: [PATCH] drm/amd/display: fix dereference before NULL check

The "plane_state" pointer was access before checking if it was NULL.

Avoid a possible NULL pointer dereference by accessing the plane
address after the check.

Addresses-Coverity-ID: 1474582 ("Dereference before null check")
Fixes: 3f68c01be9a22 ("drm/amd/display: add cyan_skillfish display support")
Signed-off-by: José Expósito <[email protected]>
---
drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
index cfd09b3f705e..fe22530242d2 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
@@ -134,11 +134,12 @@ void dcn201_update_plane_addr(const struct dc *dc, struct pipe_ctx *pipe_ctx)
PHYSICAL_ADDRESS_LOC addr;
struct dc_plane_state *plane_state = pipe_ctx->plane_state;
struct dce_hwseq *hws = dc->hwseq;
- struct dc_plane_address uma = plane_state->address;
+ struct dc_plane_address uma;

if (plane_state == NULL)
return;

+ uma = plane_state->address;
addr_patched = patch_address_for_sbs_tb_stereo(pipe_ctx, &addr);

plane_address_in_gpu_space_to_uma(hws, &uma);
--
2.25.1

2021-12-23 15:53:32

by Harry Wentland

Subject: Re: [PATCH] drm/amd/display: fix dereference before NULL check

On 2021-12-16 13:14, José Expósito wrote:
> The "plane_state" pointer was access before checking if it was NULL.
>
> Avoid a possible NULL pointer dereference by accessing the plane
> address after the check.
>
> Addresses-Coverity-ID: 1474582 ("Dereference before null check")
> Fixes: 3f68c01be9a22 ("drm/amd/display: add cyan_skillfish display support")
> Signed-off-by: José Expósito <[email protected]>

Reviewed-by: Harry Wentland <[email protected]>

Harry

> ---
> drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
> index cfd09b3f705e..fe22530242d2 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn201/dcn201_hwseq.c
> @@ -134,11 +134,12 @@ void dcn201_update_plane_addr(const struct dc *dc, struct pipe_ctx *pipe_ctx)
> PHYSICAL_ADDRESS_LOC addr;
> struct dc_plane_state *plane_state = pipe_ctx->plane_state;
> struct dce_hwseq *hws = dc->hwseq;
> - struct dc_plane_address uma = plane_state->address;
> + struct dc_plane_address uma;
>
> if (plane_state == NULL)
> return;
>
> + uma = plane_state->address;
> addr_patched = patch_address_for_sbs_tb_stereo(pipe_ctx, &addr);
>
> plane_address_in_gpu_space_to_uma(hws, &uma);