linux-kernel - [PATCH][next] drm/amd/powerplay: fix various dereferences of a pointer before it is null checked

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Date:   Thu, 12 Dec 2019 18:16:57 +0000
From:   Colin King <colin.king@...onical.com>
To:     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>,
        Kenneth Feng <kenneth.feng@....com>,
        Yintian Tao <yttao@....com>, 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/amd/powerplay: fix various dereferences of a pointer before it is null checked

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

There are several occurrances of the pointer hwmgr being dereferenced
before it is null checked.  Fix these by performing the dereference
of hwmgr after it has been null checked.

Addresses-Coverity: ("Dereference before null check")
Fixes: 8497d2bcdee1 ("drm/amd/powerplay: enable pp one vf mode for vega10")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/gpu/drm/amd/powerplay/amd_powerplay.c |  6 +++---
 drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c   | 15 +++------------
 2 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/amd/powerplay/amd_powerplay.c b/drivers/gpu/drm/amd/powerplay/amd_powerplay.c
index 5087d6bdba60..322c2015d3a0 100644
--- a/drivers/gpu/drm/amd/powerplay/amd_powerplay.c
+++ b/drivers/gpu/drm/amd/powerplay/amd_powerplay.c
@@ -275,12 +275,12 @@ static int pp_dpm_load_fw(void *handle)
 {
 	struct pp_hwmgr *hwmgr = handle;
 
-	if (!hwmgr->not_vf)
-		return 0;
-
 	if (!hwmgr || !hwmgr->smumgr_funcs || !hwmgr->smumgr_funcs->start_smu)
 		return -EINVAL;
 
+	if (!hwmgr->not_vf)
+		return 0;
+
 	if (hwmgr->smumgr_funcs->start_smu(hwmgr)) {
 		pr_err("fw load failed\n");
 		return -EINVAL;
diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c
index e2b82c902948..f48fdc7f0382 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/hwmgr.c
@@ -282,10 +282,7 @@ int hwmgr_hw_init(struct pp_hwmgr *hwmgr)
 
 int hwmgr_hw_fini(struct pp_hwmgr *hwmgr)
 {
-	if (!hwmgr->not_vf)
-		return 0;
-
-	if (!hwmgr || !hwmgr->pm_en)
+	if (!hwmgr || !hwmgr->pm_en || !hwmgr->not_vf)
 		return 0;
 
 	phm_stop_thermal_controller(hwmgr);
@@ -305,10 +302,7 @@ int hwmgr_suspend(struct pp_hwmgr *hwmgr)
 {
 	int ret = 0;
 
-	if (!hwmgr->not_vf)
-		return 0;
-
-	if (!hwmgr || !hwmgr->pm_en)
+	if (!hwmgr || !hwmgr->pm_en || !hwmgr->not_vf)
 		return 0;
 
 	phm_disable_smc_firmware_ctf(hwmgr);
@@ -327,13 +321,10 @@ int hwmgr_resume(struct pp_hwmgr *hwmgr)
 {
 	int ret = 0;
 
-	if (!hwmgr->not_vf)
-		return 0;
-
 	if (!hwmgr)
 		return -EINVAL;
 
-	if (!hwmgr->pm_en)
+	if (!hwmgr->not_vf || !hwmgr->pm_en)
 		return 0;
 
 	ret = phm_setup_asic(hwmgr);
-- 
2.24.0