drivers/amd/pm: fix a use-after-free in kv_parse_power_table

When ps allocated by kzalloc equals to NULL, kv_parse_power_table
frees adev->pm.dpm.ps that allocated before. However, after the control
flow goes through the following call chains:

kv_parse_power_table
  |-> kv_dpm_init
        |-> kv_dpm_sw_init
	      |-> kv_dpm_fini

The adev->pm.dpm.ps is used in the for loop of kv_dpm_fini after its
first free in kv_parse_power_table and causes a use-after-free bug.

Fixes: a2e73f5 ("drm/amdgpu: Add support for CIK parts")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: AlexiousLu

drivers/gpu/drm/amd/pm/legacy-dpm/kv_dpm.c

@@ -2735,10 +2735,8 @@ static int kv_parse_power_table(struct amdgpu_device *adev)
 		non_clock_info = (struct _ATOM_PPLIB_NONCLOCK_INFO *)
 			&non_clock_info_array->nonClockInfo[non_clock_array_index];
 		ps = kzalloc(sizeof(struct kv_ps), GFP_KERNEL);
-		if (ps == NULL) {
-			kfree(adev->pm.dpm.ps);
+		if (ps == NULL)
 			return -ENOMEM;
-		}
 		adev->pm.dpm.ps[i].ps_priv = ps;
 		k = 0;
 		idx = (u8 *)&power_state->v2.clockInfoIndex[0];