2022-12-06 11:04:43

by Denis Arefev

Subject: [PATCH] drm/amd/display: Added pointer check

Return value of a function 'dc_create_state' is
dereferenced at amdgpu_dm.c:2027 without checking for null

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Denis Arefev <[email protected]>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 0f7749e9424d..529483997154 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1960,7 +1960,9 @@ static int dm_resume(void *handle)
dc_release_state(dm_state->context);
dm_state->context = dc_create_state(dm->dc);
/* TODO: Remove dc_state->dccg, use dc->dccg directly. */
- dc_resource_state_construct(dm->dc, dm_state->context);
+ if (dm_state->context) {
+ dc_resource_state_construct(dm->dc, dm_state->context);
+ }

/* Before powering on DC we need to re-initialize DMUB. */
r = dm_dmub_hw_init(adev);
--
2.25.1

2022-12-06 11:38:56

by Christian König

Subject: Re: [PATCH] drm/amd/display: Added pointer check

Am 06.12.22 um 11:47 schrieb Denis Arefev:
> Return value of a function 'dc_create_state' is
> dereferenced at amdgpu_dm.c:2027 without checking for null
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Signed-off-by: Denis Arefev <[email protected]>
> ---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 0f7749e9424d..529483997154 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1960,7 +1960,9 @@ static int dm_resume(void *handle)
> dc_release_state(dm_state->context);
> dm_state->context = dc_create_state(dm->dc);
> /* TODO: Remove dc_state->dccg, use dc->dccg directly. */
> - dc_resource_state_construct(dm->dc, dm_state->context);
> + if (dm_state->context) {
> + dc_resource_state_construct(dm->dc, dm_state->context);
> + }

Single line statements shouldn't have an {} around them.

Apart from that I think error handling when dm_state->context can't be
created would be more appropriate, but that's something our display team
needs to look at.

Regards,
Christian.

>
> /* Before powering on DC we need to re-initialize DMUB. */
> r = dm_dmub_hw_init(adev);