Re: [PATCH] drm/amdgpu: Fixes uninitialized variable usage in amdgpu_dm_setup_replay
From: Christian König
Date: Mon Oct 30 2023 - 11:52:36 EST
Am 28.10.23 um 02:48 schrieb Yuran Pereira:
Hello,
On Fri, Oct 27, 2023 at 11:57:45AM -0400, Hamza Mahfooz wrote:
On 10/27/23 11:55, Lakha, Bhawanpreet wrote:
[AMD Official Use Only - General]
There was a consensus to use memset instead of {0}. I remember making
changes related to that previously.
Hm, seems like it's used rather consistently in the DM and in DC
though.
Have you decided which one should be used?
Should I submit a v2 patch using {0} instead of memset?
The problem is that {0} doesn't initialize padding fields in structures.
So what can happen are problems like leaking bytes to userspace or
getting unstable hash keys etc...
So I think memset() is usually preferred and that not only counts for Linux.
Regards,
Christian.
Yuran Pereira
Bhawan
------------------------------------------------------------------------
*From:* Mahfooz, Hamza <Hamza.Mahfooz@xxxxxxx>
*Sent:* October 27, 2023 11:53 AM
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*Cc:* Li, Sun peng (Leo) <Sunpeng.Li@xxxxxxx>; Lakha, Bhawanpreet
<Bhawanpreet.Lakha@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>; Siqueira,
Rodrigo <Rodrigo.Siqueira@xxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
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<Alexander.Deucher@xxxxxxx>; Koenig, Christian
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*Subject:* Re: [PATCH] drm/amdgpu: Fixes uninitialized variable usage in
amdgpu_dm_setup_replay
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
--
Hamza