2023-04-26 19:25:25

by Harshit Mogalapalli

Subject: [PATCH next] drm/amd/display: Fix possible NULL dereference in dc_dmub_srv_cmd_run_list()

We have a NULL check for 'dc_dmub_srv' in dc_dmub_srv_cmd_run_list()
but we are dereferencing it before checking.

Fix this moving the dereference next to NULL check.

This issue is found with Smatch(static analysis tool).

Fixes: e97cc04fe0fb ("drm/amd/display: refactor dmub commands into single function")
Signed-off-by: Harshit Mogalapalli <[email protected]>
---
Only compile tested.
---
drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
index d15ec32243e2..62d3473c32bc 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
@@ -125,7 +125,7 @@ bool dc_dmub_srv_cmd_run(struct dc_dmub_srv *dc_dmub_srv, union dmub_rb_cmd *cmd

bool dc_dmub_srv_cmd_run_list(struct dc_dmub_srv *dc_dmub_srv, unsigned int count, union dmub_rb_cmd *cmd_list, enum dm_dmub_wait_type wait_type)
{
- struct dc_context *dc_ctx = dc_dmub_srv->ctx;
+ struct dc_context *dc_ctx;
struct dmub_srv *dmub;
enum dmub_status status;
int i;
@@ -133,6 +133,7 @@ bool dc_dmub_srv_cmd_run_list(struct dc_dmub_srv *dc_dmub_srv, unsigned int coun
if (!dc_dmub_srv || !dc_dmub_srv->dmub)
return false;

+ dc_ctx = dc_dmub_srv->ctx;
dmub = dc_dmub_srv->dmub;

for (i = 0 ; i < count; i++) {
--
2.38.1

2023-04-26 21:09:03

by Hamza Mahfooz

Subject: Re: [PATCH next] drm/amd/display: Fix possible NULL dereference in dc_dmub_srv_cmd_run_list()

On 4/26/23 15:24, Harshit Mogalapalli wrote:
> We have a NULL check for 'dc_dmub_srv' in dc_dmub_srv_cmd_run_list()
> but we are dereferencing it before checking.
>
> Fix this moving the dereference next to NULL check.
>
> This issue is found with Smatch(static analysis tool).
>
> Fixes: e97cc04fe0fb ("drm/amd/display: refactor dmub commands into single function")
> Signed-off-by: Harshit Mogalapalli <[email protected]>

Applied, thanks!

> ---
> Only compile tested.
> ---
> drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
> index d15ec32243e2..62d3473c32bc 100644
> --- a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
> +++ b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
> @@ -125,7 +125,7 @@ bool dc_dmub_srv_cmd_run(struct dc_dmub_srv *dc_dmub_srv, union dmub_rb_cmd *cmd
>
> bool dc_dmub_srv_cmd_run_list(struct dc_dmub_srv *dc_dmub_srv, unsigned int count, union dmub_rb_cmd *cmd_list, enum dm_dmub_wait_type wait_type)
> {
> - struct dc_context *dc_ctx = dc_dmub_srv->ctx;
> + struct dc_context *dc_ctx;
> struct dmub_srv *dmub;
> enum dmub_status status;
> int i;
> @@ -133,6 +133,7 @@ bool dc_dmub_srv_cmd_run_list(struct dc_dmub_srv *dc_dmub_srv, unsigned int coun
> if (!dc_dmub_srv || !dc_dmub_srv->dmub)
> return false;
>
> + dc_ctx = dc_dmub_srv->ctx;
> dmub = dc_dmub_srv->dmub;
>
> for (i = 0 ; i < count; i++) {
--
Hamza