Patch "drm/amd/display: Check index msg_id before read or write" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amd/display: Check index msg_id before read or write

to the 6.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-check-index-msg_id-before-read-or-wr.patch
and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 0fb3c7af48a7d8d384550f14d52afe4a4413335a
Author: Alex Hung <alex.hung@xxxxxxx>
Date:   Thu Apr 18 13:27:43 2024 -0600

    drm/amd/display: Check index msg_id before read or write
    
    [ Upstream commit 59d99deb330af206a4541db0c4da8f73880fba03 ]
    
    [WHAT]
    msg_id is used as an array index and it cannot be a negative value, and
    therefore cannot be equal to MOD_HDCP_MESSAGE_ID_INVALID (-1).
    
    [HOW]
    Check whether msg_id is valid before reading and setting.
    
    This fixes 4 OVERRUN issues reported by Coverity.
    
    Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@xxxxxxx>
    Acked-by: Wayne Lin <wayne.lin@xxxxxxx>
    Signed-off-by: Alex Hung <alex.hung@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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 f7b5583ee609a..8e9caae7c9559 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c
@@ -156,6 +156,10 @@ 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) {
+		return MOD_HDCP_STATUS_DDC_FAILURE;
+	}
+
 	if (is_dp_hdcp(hdcp)) {
 		while (buf_len > 0) {
 			cur_size = MIN(buf_len, HDCP_MAX_AUX_TRANSACTION_SIZE);
@@ -215,6 +219,10 @@ 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) {
+		return MOD_HDCP_STATUS_DDC_FAILURE;
+	}
+
 	if (is_dp_hdcp(hdcp)) {
 		while (buf_len > 0) {
 			cur_size = MIN(buf_len, HDCP_MAX_AUX_TRANSACTION_SIZE);