[PATCH ] drm/radeon: Fix potential buffer overflow in ci_set_mc_special_registers()

[chenmaodong]

Hi,

The length of table->mc_reg_address is SMU7_DISCRETE_MC_REGISTER_ARRAY_SIZE.

In ci_set_mc_special_registers(), the boundary checking

here("if (j > SMU7_DISCRETE_MC_REGISTER_ARRAY_SIZE)") allows 'j' equal to

SMU7_DISCRETE_MC_REGISTER_ARRAY_SIZE which can easily cause the 

table->mc_reg_address to read out of bounds. 

To solve this problem, we change ">" to ">=" and check this boundary 

of table->mc_reg_address after "pi->mem_gddr5" is false.

Signed-off-by: chenmaodong <chenmaodong at huawei.com>
---
 drivers/gpu/drm/radeon/ci_dpm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/ci_dpm.c b/drivers/gpu/drm/radeon/ci_dpm.c
index a97294a..42ef745a 100644
--- a/drivers/gpu/drm/radeon/ci_dpm.c
+++ b/drivers/gpu/drm/radeon/ci_dpm.c
@@ -4364,10 +4364,10 @@ static int ci_set_mc_special_registers(struct radeon_device *rdev,
 					table->mc_reg_table_entry[k].mc_data[j] |= 0x100;
 			}
 			j++;
-			if (j > SMU7_DISCRETE_MC_REGISTER_ARRAY_SIZE)
-				return -EINVAL;
 
 			if (!pi->mem_gddr5) {
+				if (j >= SMU7_DISCRETE_MC_REGISTER_ARRAY_SIZE)
+					return -EINVAL;
 				table->mc_reg_address[j].s1 = MC_PMG_AUTO_CMD >> 2;
 				table->mc_reg_address[j].s0 = MC_PMG_AUTO_CMD >> 2;
 				for (k = 0; k < table->num_entries; k++) {
-- 
2.7.4