linux-kernel - [PATCH][next] drm/amdgpu/powerplay: fix dereference before null check of pointer hwmgr

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Date:   Fri, 15 Nov 2019 09:47:54 +0000
From:   Colin King <colin.king@...onical.com>
To:     Rex Zhu <rex.zhu@....com>, Evan Quan <evan.quan@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Zhou <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] drm/amdgpu/powerplay: fix dereference before null check of pointer hwmgr

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

The assignment of adev dereferences pointer hwmgr before hwmgr is null
checked, hence there is a potential null pointer deference issue. Fix
this by assigning adev after the null check.

Addresses-Coverity: ("Dereference before null check")
Fixes: 0896d2f7ba4d ("drm/amdgpu/powerplay: properly set PP_GFXOFF_MASK")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c
index 443625c83ec9..d2909c91d65b 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c
@@ -81,7 +81,7 @@ static void hwmgr_init_workload_prority(struct pp_hwmgr *hwmgr)
 
 int hwmgr_early_init(struct pp_hwmgr *hwmgr)
 {
-	struct amdgpu_device *adev = hwmgr->adev;
+	struct amdgpu_device *adev;
 
 	if (!hwmgr)
 		return -EINVAL;
@@ -96,6 +96,8 @@ int hwmgr_early_init(struct pp_hwmgr *hwmgr)
 	hwmgr_init_workload_prority(hwmgr);
 	hwmgr->gfxoff_state_changed_by_workload = false;
 
+	adev = hwmgr->adev;
+
 	switch (hwmgr->chip_family) {
 	case AMDGPU_FAMILY_CI:
 		adev->pm.pp_feature &= ~PP_GFXOFF_MASK;
-- 
2.20.1