[PATCH 20/45] drm/amd/display: Add array index check for hdcp ddc access

[Tom Chung]

From: Hersen Wu <hersenxs.wu at amd.com>

[Why]
Coverity reports OVERRUN warning. Do not check if array
index valid.

[How]
Check msg_id valid and valid array index.

Reviewed-by: Alex Hung <alex.hung at amd.com>
Acked-by: Tom Chung <chiahsuan.chung at amd.com>
Signed-off-by: Hersen Wu <hersenxs.wu at amd.com>
---
 .../drm/amd/display/modules/hdcp/hdcp_ddc.c   | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
index 8e9caae7c955..1b2df97226a3 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
@@ -156,11 +156,16 @@ static enum mod_hdcp_status read(struct mod_hdcp *hdcp,
 	uint32_t cur_size = 0;
 	uint32_t data_offset = 0;
 
-	if (msg_id == MOD_HDCP_MESSAGE_ID_INVALID) {
+	if (msg_id == MOD_HDCP_MESSAGE_ID_INVALID ||
+		msg_id >= MOD_HDCP_MESSAGE_ID_MAX)
 		return MOD_HDCP_STATUS_DDC_FAILURE;
-	}
 
 	if (is_dp_hdcp(hdcp)) {
+		int num_dpcd_addrs = sizeof(hdcp_dpcd_addrs) /
+			sizeof(hdcp_dpcd_addrs[0]);
+		if (msg_id >= num_dpcd_addrs)
+			return MOD_HDCP_STATUS_DDC_FAILURE;
+
 		while (buf_len > 0) {
 			cur_size = MIN(buf_len, HDCP_MAX_AUX_TRANSACTION_SIZE);
 			success = hdcp->config.ddc.funcs.read_dpcd(hdcp->config.ddc.handle,
@@ -175,6 +180,11 @@ static enum mod_hdcp_status read(struct mod_hdcp *hdcp,
 			data_offset += cur_size;
 		}
 	} else {
+		int num_i2c_offsets = sizeof(hdcp_i2c_offsets) /
+			sizeof(hdcp_i2c_offsets[0]);
+		if (msg_id >= num_i2c_offsets)
+			return MOD_HDCP_STATUS_DDC_FAILURE;
+
 		success = hdcp->config.ddc.funcs.read_i2c(
 				hdcp->config.ddc.handle,
 				HDCP_I2C_ADDR,
@@ -219,11 +229,16 @@ static enum mod_hdcp_status write(struct mod_hdcp *hdcp,
 	uint32_t cur_size = 0;
 	uint32_t data_offset = 0;
 
-	if (msg_id == MOD_HDCP_MESSAGE_ID_INVALID) {
+	if (msg_id == MOD_HDCP_MESSAGE_ID_INVALID ||
+		msg_id >= MOD_HDCP_MESSAGE_ID_MAX)
 		return MOD_HDCP_STATUS_DDC_FAILURE;
-	}
 
 	if (is_dp_hdcp(hdcp)) {
+		int num_dpcd_addrs = sizeof(hdcp_dpcd_addrs) /
+			sizeof(hdcp_dpcd_addrs[0]);
+		if (msg_id >= num_dpcd_addrs)
+			return MOD_HDCP_STATUS_DDC_FAILURE;
+
 		while (buf_len > 0) {
 			cur_size = MIN(buf_len, HDCP_MAX_AUX_TRANSACTION_SIZE);
 			success = hdcp->config.ddc.funcs.write_dpcd(
@@ -239,6 +254,11 @@ static enum mod_hdcp_status write(struct mod_hdcp *hdcp,
 			data_offset += cur_size;
 		}
 	} else {
+		int num_i2c_offsets = sizeof(hdcp_i2c_offsets) /
+			sizeof(hdcp_i2c_offsets[0]);
+		if (msg_id >= num_i2c_offsets)
+			return MOD_HDCP_STATUS_DDC_FAILURE;
+
 		hdcp->buf[0] = hdcp_i2c_offsets[msg_id];
 		memmove(&hdcp->buf[1], buf, buf_len);
 		success = hdcp->config.ddc.funcs.write_i2c(
-- 
2.34.1