Re: [PATCH] drm/amdgpu: Fixes uninitialized variable usage in amdgpu_dm_setup_replay

[Hamza Mahfooz]

Also, please write the tagline in present tense.
On 10/27/23 11:53, Hamza Mahfooz wrote:
> On 10/26/23 17:25, Yuran Pereira wrote:
> > Since `pr_config` is not initialized after its declaration, the
> > following operations with `replay_enable_option` may be performed
> > when `replay_enable_option` is holding junk values which could
> > possibly lead to undefined behaviour
> >
> > ```
> >      ...
> >      pr_config.replay_enable_option |= pr_enable_option_static_screen;
> >      ...
> >
> >      if (!pr_config.replay_timing_sync_supported)
> >          pr_config.replay_enable_option &= ~pr_enable_option_general_ui;
> >      ...
> > ```
> >
> > This patch initializes `pr_config` after its declaration to ensure that
> > it doesn't contain junk data, and prevent any undefined behaviour
> >
> > Addresses-Coverity-ID: 1544428 ("Uninitialized scalar variable")
> > Fixes: dede1fea4460 ("drm/amd/display: Add Freesync Panel DM code")
> > Signed-off-by: Yuran Pereira <yuran.pereira@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_replay.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_replay.c 
> > b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_replay.c
> > index 32d3086c4cb7..40526507f50b 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_replay.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_replay.c
> > @@ -23,6 +23,7 @@
> >    *
> >    */
> > +#include <linux/string.h>
> >   #include "amdgpu_dm_replay.h"
> >   #include "dc.h"
> >   #include "dm_helpers.h"
> > @@ -74,6 +75,8 @@ bool amdgpu_dm_setup_replay(struct dc_link *link, 
> > struct amdgpu_dm_connector *ac
> >       struct replay_config pr_config;
>
> I would prefer setting pr_config = {0};
>
> >       union replay_debug_flags *debug_flags = NULL;
> > +    memset(&pr_config, 0, sizeof(pr_config));
> > +
> >       // For eDP, if Replay is supported, return true to skip checks
> >       if (link->replay_settings.config.replay_supported)
> >           return true;
--
Hamza