drm/amd/display: Fix Null Pointer Dereference Issues

[PATCH 1/2] drm/amd/display: Fix null check for pipe_ctx->plane_state in dcn20_program_pipe

Posted by Zicheng Qu 2 weeks, 4 days ago

This commit addresses a null pointer dereference issue in
dcn20_program_pipe(). Previously, commit 8e4ed3cf1642 ("drm/amd/display:
Add null check for pipe_ctx->plane_state in dcn20_program_pipe")
partially fixed the null pointer dereference issue. However, in
dcn20_update_dchubp_dpp(), the variable pipe_ctx is passed in, and
plane_state is accessed again through pipe_ctx. Multiple if statements
directly call attributes of plane_state, leading to potential null
pointer dereference issues. This patch adds necessary null checks to
ensure stability.

Fixes: 8e4ed3cf1642 ("drm/amd/display: Add null check for pipe_ctx->plane_state in dcn20_program_pipe")
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
---
 drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
index a80c08582932..36d12db8d022 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
@@ -1923,9 +1923,9 @@ static void dcn20_program_pipe(
 				dc->res_pool->hubbub, pipe_ctx->plane_res.hubp->inst, pipe_ctx->hubp_regs.det_size);
 	}
 
-	if (pipe_ctx->update_flags.raw ||
-	    (pipe_ctx->plane_state && pipe_ctx->plane_state->update_flags.raw) ||
-	    pipe_ctx->stream->update_flags.raw)
+	if (pipe_ctx->plane_state && (pipe_ctx->update_flags.raw ||
+	    pipe_ctx->plane_state->update_flags.raw ||
+	    pipe_ctx->stream->update_flags.raw))
 		dcn20_update_dchubp_dpp(dc, pipe_ctx, context);
 
 	if (pipe_ctx->plane_state && (pipe_ctx->update_flags.bits.enable ||
-- 
2.34.1

Re: [PATCH 1/2] drm/amd/display: Fix null check for pipe_ctx->plane_state in dcn20_program_pipe

Posted by Chung, ChiaHsuan (Tom) 1 week, 3 days ago

Reviewed-by: Tom Chung <chiahsuan.chung@amd.com>

On 11/5/2024 10:01 PM, Zicheng Qu wrote:
> This commit addresses a null pointer dereference issue in
> dcn20_program_pipe(). Previously, commit 8e4ed3cf1642 ("drm/amd/display:
> Add null check for pipe_ctx->plane_state in dcn20_program_pipe")
> partially fixed the null pointer dereference issue. However, in
> dcn20_update_dchubp_dpp(), the variable pipe_ctx is passed in, and
> plane_state is accessed again through pipe_ctx. Multiple if statements
> directly call attributes of plane_state, leading to potential null
> pointer dereference issues. This patch adds necessary null checks to
> ensure stability.
>
> Fixes: 8e4ed3cf1642 ("drm/amd/display: Add null check for pipe_ctx->plane_state in dcn20_program_pipe")
> Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
> ---
>   drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
> index a80c08582932..36d12db8d022 100644
> --- a/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
> +++ b/drivers/gpu/drm/amd/display/dc/hwss/dcn20/dcn20_hwseq.c
> @@ -1923,9 +1923,9 @@ static void dcn20_program_pipe(
>   				dc->res_pool->hubbub, pipe_ctx->plane_res.hubp->inst, pipe_ctx->hubp_regs.det_size);
>   	}
>   
> -	if (pipe_ctx->update_flags.raw ||
> -	    (pipe_ctx->plane_state && pipe_ctx->plane_state->update_flags.raw) ||
> -	    pipe_ctx->stream->update_flags.raw)
> +	if (pipe_ctx->plane_state && (pipe_ctx->update_flags.raw ||
> +	    pipe_ctx->plane_state->update_flags.raw ||
> +	    pipe_ctx->stream->update_flags.raw))
>   		dcn20_update_dchubp_dpp(dc, pipe_ctx, context);
>   
>   	if (pipe_ctx->plane_state && (pipe_ctx->update_flags.bits.enable ||

[PATCH 1/2] drm/amd/display: Fix null check for pipe_ctx->plane_state in dcn20_program_pipe
[PATCH 2/2] drm/amd/display: Fix null check for pipe_ctx->plane_state in hwss_setup_dpp