linux-kernel - [PATCH] drm/amd/powerplay: Variable ps could be NULL when it get dereferenced

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Date:   Thu, 29 Aug 2019 21:35:04 -0700
From:   Yizhuo <yzhai003@....edu>
To:     unlisted-recipients:; (no To-header on input)
Cc:     csong@...ucr.edu, zhiyunq@...ucr.edu, Yizhuo <yzhai003@....edu>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/amd/powerplay: Variable ps could be NULL when it get dereferenced

Inside function cz_get_performance_level(), pointer ps could be NULL via
cast_const_PhwCzPowerState(). However, this pointer is dereferenced
without any check, which is potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@....edu>
---
 drivers/gpu/drm/amd/powerplay/hwmgr/cz_hwmgr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/cz_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/cz_hwmgr.c
index bc839ff0bdd0..d2628e7b612d 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/cz_hwmgr.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/cz_hwmgr.c
@@ -1799,6 +1799,9 @@ static int cz_get_performance_level(struct pp_hwmgr *hwmgr, const struct pp_hw_p
 	data = (struct cz_hwmgr *)(hwmgr->backend);
 	ps = cast_const_PhwCzPowerState(state);
 
+	if (!ps)
+		return -EINVAL;
+
 	level_index = index > ps->level - 1 ? ps->level - 1 : index;
 	level->coreClock = ps->levels[level_index].engineClock;
 
-- 
2.17.1