[SRU][F][PATCH 1/1] drm/panel: fix a possible null pointer dereference

[Massimiliano Pellizzer]

From: Ma Ke <make_ruc2021 at 163.com>

In versatile_panel_get_modes(), the return value of drm_mode_duplicate()
is assigned to mode, which will lead to a NULL pointer dereference
on failure of drm_mode_duplicate(). Add a check to avoid npd.

Signed-off-by: Ma Ke <make_ruc2021 at 163.com>
Reviewed-by: Neil Armstrong <neil.armstrong at linaro.org>
Link: https://lore.kernel.org/r/20231007033105.3997998-1-make_ruc2021@163.com
Signed-off-by: Neil Armstrong <neil.armstrong at linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231007033105.3997998-1-make_ruc2021@163.com
(backported from commit 924e5814d1f84e6fa5cb19c6eceb69f066225229)
[mpellizzer: backported solving merge conflicts due to surrounding
instructions which do not affect the patch]
CVE-2023-52821
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 drivers/gpu/drm/panel/panel-arm-versatile.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-arm-versatile.c b/drivers/gpu/drm/panel/panel-arm-versatile.c
index a0574dc03e16..33febcb08f8b 100644
--- a/drivers/gpu/drm/panel/panel-arm-versatile.c
+++ b/drivers/gpu/drm/panel/panel-arm-versatile.c
@@ -271,6 +271,8 @@ static int versatile_panel_get_modes(struct drm_panel *panel)
 	connector->display_info.bus_flags = vpanel->panel_type->bus_flags;
 
 	mode = drm_mode_duplicate(panel->drm, &vpanel->panel_type->mode);
+	if (!mode)
+		return -ENOMEM;
 	drm_mode_set_name(mode);
 	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
 
-- 
2.43.0