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

[Tom Chung]

From: Hersen Wu <hersenxs...@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.h...@amd.com>
Acked-by: Tom Chung <chiahsuan.ch...@amd.com>
Signed-off-by: Hersen Wu <hersenxs...@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