FAILED: patch "[PATCH] drm/amd/display: Add null pointer check for" failed to apply to 5.10-stable tree

FAILED: patch "[PATCH] drm/amd/display: Add null pointer check for" failed to apply to 5.10-stable tree

[gregkh]

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x c3e9826a22027a21d998d3e64882fa377b613006
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025063028-crayon-registry-8ae0@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c3e9826a22027a21d998d3e64882fa377b613006 Mon Sep 17 00:00:00 2001
From: Wentao Liang <vulab@iscas.ac.cn>
Date: Mon, 26 May 2025 10:37:31 +0800
Subject: [PATCH] drm/amd/display: Add null pointer check for
 get_first_active_display()

The function mod_hdcp_hdcp1_enable_encryption() calls the function
get_first_active_display(), but does not check its return value.
The return value is a null pointer if the display list is empty.
This will lead to a null pointer dereference in
mod_hdcp_hdcp2_enable_encryption().

Add a null pointer check for get_first_active_display() and return
MOD_HDCP_STATUS_DISPLAY_NOT_FOUND if the function return null.

Fixes: 2deade5ede56 ("drm/amd/display: Remove hdcp display state with mst fix")
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org # v5.8

diff --git a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
index 8c137d7c032e..e58e7b93810b 100644
--- a/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
+++ b/drivers/gpu/drm/amd/display/modules/hdcp/hdcp_psp.c
@@ -368,6 +368,9 @@ enum mod_hdcp_status mod_hdcp_hdcp1_enable_encryption(struct mod_hdcp *hdcp)
 	struct mod_hdcp_display *display = get_first_active_display(hdcp);
 	enum mod_hdcp_status status = MOD_HDCP_STATUS_SUCCESS;
 
+	if (!display)
+		return MOD_HDCP_STATUS_DISPLAY_NOT_FOUND;
+
 	mutex_lock(&psp->hdcp_context.mutex);
 	hdcp_cmd = (struct ta_hdcp_shared_memory *)psp->hdcp_context.context.mem_context.shared_buf;
 	memset(hdcp_cmd, 0, sizeof(struct ta_hdcp_shared_memory));