[PATCH] drm/amd/amdgpu: default to zero number of states if not enabled

[Colin King <colin.king@canonical.com>]

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

Currently, if adev->pp_enabled is false then the pp_stats_info data
is not read and hence a garbage number of states from the stack
is used to dump out the number of states. Given data.nums could be
any random value, this could easily lead to read outside the
data.states array.  Fix this by setting data.nums to zero if
adev->pp_enabled is false.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
index accc908..808d788 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
@@ -195,6 +195,8 @@ static ssize_t amdgpu_get_pp_num_states(struct device *dev,
 
 	if (adev->pp_enabled)
 		amdgpu_dpm_get_pp_num_states(adev, &data);
+	else
+		data.nums = 0;
 
 	buf_len = snprintf(buf, PAGE_SIZE, "states: %d\n", data.nums);
 	for (i = 0; i < data.nums; i++)
-- 
2.9.3