linux-kernel - [PATCH AUTOSEL 6.10 017/121] drm/amd/display: Add array index check for hdcp ddc access

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Message-ID: <20240801000834.3930818-17-sashal@kernel.org>
Date: Wed, 31 Jul 2024 19:59:15 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Hersen Wu <hersenxs.wu@....com>,
	Alex Hung <alex.hung@....com>,
	Tom Chung <chiahsuan.chung@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	harry.wentland@....com,
	sunpeng.li@....com,
	Rodrigo.Siqueira@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	jiapeng.chong@...ux.alibaba.com,
	wayne.lin@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.10 017/121] drm/amd/display: Add array index check for hdcp ddc access

From: Hersen Wu <hersenxs.wu@....com>

[ Upstream commit 4e70c0f5251c25885c31ee84a31f99a01f7cf50e ]

[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@....com>
Acked-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Hersen Wu <hersenxs.wu@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../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 8e9caae7c9559..1b2df97226a3f 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(
-- 
2.43.0