linux-kernel - [PATCH] drm/amdgpu: Fixes uninitialized variable usage in amdgpu_dm_setup

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Message-ID: <DB3PR10MB683590457246A6625BAA6102E8DDA@DB3PR10MB6835.EURPRD10.PROD.OUTLOOK.COM>
Date:   Fri, 27 Oct 2023 02:55:22 +0530
From:   Yuran Pereira <yuran.pereira@...mail.com>
To:     airlied@...il.com
Cc:     Yuran Pereira <yuran.pereira@...mail.com>, harry.wentland@....com,
        sunpeng.li@....com, Rodrigo.Siqueira@....com,
        alexander.deucher@....com, christian.koenig@....com,
        Xinhui.Pan@....com, daniel@...ll.ch, Bhawanpreet.Lakha@....com,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: [PATCH] drm/amdgpu: Fixes uninitialized variable usage in amdgpu_dm_setup_replay

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@...mail.com>
---
 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;
 	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;
-- 
2.25.1