2021-11-15 08:10:56

by Yang Li

Subject: [PATCH -next] drm/amd/display: check top_pipe_to_program pointer

Clang static analysis reports this error

drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:2870:7: warning:
Dereference of null pointer [clang-analyzer-core.NullDereference]
if
(top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
^

top_pipe_to_program being NULL is caught as an error
But then it is used to report the error.

So add a check before using it.

Reported-by: Abaci Robot <[email protected]>
Signed-off-by: Yang Li <[email protected]>
---
drivers/gpu/drm/amd/display/dc/core/dc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 39ad385..34382d0 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -2867,7 +2867,8 @@ static void commit_planes_for_stream(struct dc *dc,
#endif

if ((update_type != UPDATE_TYPE_FAST) && stream->update_flags.bits.dsc_changed)
- if (top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
+ if (top_pipe_to_program &&
+ top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
if (should_use_dmub_lock(stream->link)) {
union dmub_hw_lock_flags hw_locks = { 0 };
struct dmub_hw_lock_inst_flags inst_flags = { 0 };
--
1.8.3.1

2021-11-17 21:40:46

by Alex Deucher

Subject: Re: [PATCH -next] drm/amd/display: check top_pipe_to_program pointer

Applied. Thanks!

On Mon, Nov 15, 2021 at 3:10 AM Yang Li <[email protected]> wrote:
>
> Clang static analysis reports this error
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:2870:7: warning:
> Dereference of null pointer [clang-analyzer-core.NullDereference]
> if
> (top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
> ^
>
> top_pipe_to_program being NULL is caught as an error
> But then it is used to report the error.
>
> So add a check before using it.
>
> Reported-by: Abaci Robot <[email protected]>
> Signed-off-by: Yang Li <[email protected]>
> ---
> drivers/gpu/drm/amd/display/dc/core/dc.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
> index 39ad385..34382d0 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
> @@ -2867,7 +2867,8 @@ static void commit_planes_for_stream(struct dc *dc,
> #endif
>
> if ((update_type != UPDATE_TYPE_FAST) && stream->update_flags.bits.dsc_changed)
> - if (top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
> + if (top_pipe_to_program &&
> + top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
> if (should_use_dmub_lock(stream->link)) {
> union dmub_hw_lock_flags hw_locks = { 0 };
> struct dmub_hw_lock_inst_flags inst_flags = { 0 };
> --
> 1.8.3.1
>