[PATCH][next] drm/amd/display: fix dereference of pointer aconnector when it is null

[PATCH][next] drm/amd/display: fix dereference of pointer aconnector when it is null

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently pointer aconnector is being dereferenced by the call to
to_dm_connector_state before it is being null checked, this could
lead to a null pointer dereference.  Fix this by checking that
aconnector is null before dereferencing it.

Addresses-Coverity: ("Dereference before null check")
Fixes: 5133c6241d9c ("drm/amd/display: Add MST atomic routines")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index e3cda6984d28..72e677796a48 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -193,12 +193,11 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
 	 * that blocks before commit guaranteeing that the state
 	 * is not gonna be swapped while still in use in commit tail */
 
-	dm_conn_state = to_dm_connector_state(aconnector->base.state);
-
-
 	if (!aconnector || !aconnector->mst_port)
 		return false;
 
+	dm_conn_state = to_dm_connector_state(aconnector->base.state);
+
 	mst_mgr = &aconnector->mst_port->mst_mgr;
 
 	if (!mst_mgr->mst_state)
-- 
2.20.1

Re: [PATCH][next] drm/amd/display: fix dereference of pointer aconnector when it is null

[Mikita Lipski]

Thanks!

Reviewed-by: Mikita Lipski <mikita.lipski@amd.com>

On 08.11.2019 9:38, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Currently pointer aconnector is being dereferenced by the call to
> to_dm_connector_state before it is being null checked, this could
> lead to a null pointer dereference.  Fix this by checking that
> aconnector is null before dereferencing it.
> 
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 5133c6241d9c ("drm/amd/display: Add MST atomic routines")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> index e3cda6984d28..72e677796a48 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> @@ -193,12 +193,11 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
>   	 * that blocks before commit guaranteeing that the state
>   	 * is not gonna be swapped while still in use in commit tail */
>   
> -	dm_conn_state = to_dm_connector_state(aconnector->base.state);
> -
> -
>   	if (!aconnector || !aconnector->mst_port)
>   		return false;
>   
> +	dm_conn_state = to_dm_connector_state(aconnector->base.state);
> +
>   	mst_mgr = &aconnector->mst_port->mst_mgr;
>   
>   	if (!mst_mgr->mst_state)
> 

-- 
Thanks,
Mikita Lipski
mikita.lipski@amd.com

Re: [PATCH][next] drm/amd/display: fix dereference of pointer aconnector when it is null

[Alex Deucher]

Applied.  thanks!

Alex

On Fri, Nov 8, 2019 at 9:42 AM Mikita Lipski <mlipski@amd.com> wrote:
>
> Thanks!
>
> Reviewed-by: Mikita Lipski <mikita.lipski@amd.com>
>
> On 08.11.2019 9:38, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> >
> > Currently pointer aconnector is being dereferenced by the call to
> > to_dm_connector_state before it is being null checked, this could
> > lead to a null pointer dereference.  Fix this by checking that
> > aconnector is null before dereferencing it.
> >
> > Addresses-Coverity: ("Dereference before null check")
> > Fixes: 5133c6241d9c ("drm/amd/display: Add MST atomic routines")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > ---
> >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 5 ++---
> >   1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > index e3cda6984d28..72e677796a48 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
> > @@ -193,12 +193,11 @@ bool dm_helpers_dp_mst_write_payload_allocation_table(
> >        * that blocks before commit guaranteeing that the state
> >        * is not gonna be swapped while still in use in commit tail */
> >
> > -     dm_conn_state = to_dm_connector_state(aconnector->base.state);
> > -
> > -
> >       if (!aconnector || !aconnector->mst_port)
> >               return false;
> >
> > +     dm_conn_state = to_dm_connector_state(aconnector->base.state);
> > +
> >       mst_mgr = &aconnector->mst_port->mst_mgr;
> >
> >       if (!mst_mgr->mst_state)
> >
>
> --
> Thanks,
> Mikita Lipski
> mikita.lipski@amd.com
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