FAILED: patch "[PATCH] drm/sysfb: Do not dereference NULL pointer in plane reset" failed to apply to 6.1-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.1-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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 14e02ed3876f4ab0ed6d3f41972175f8b8df3d70
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025110312-duration-shape-5d38@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 14e02ed3876f4ab0ed6d3f41972175f8b8df3d70 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: Fri, 17 Oct 2025 11:13:36 +0200
Subject: [PATCH] drm/sysfb: Do not dereference NULL pointer in plane reset

The plane state in __drm_gem_reset_shadow_plane() can be NULL. Do not
deref that pointer, but forward NULL to the other plane-reset helpers.
Clears plane->state to NULL.

v2:
- fix typo in commit description (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: b71565022031 ("drm/gem: Export implementation of shadow-plane helpers")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/dri-devel/aPIDAsHIUHp_qSW4@stanley.mountain/
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Melissa Wen <melissa.srw@gmail.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.15+
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patch.msgid.link/20251017091407.58488-1-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
index ebf305fb24f0..6fb55601252f 100644
--- a/drivers/gpu/drm/drm_gem_atomic_helper.c
+++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
@@ -310,8 +310,12 @@ EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
 void __drm_gem_reset_shadow_plane(struct drm_plane *plane,
 				  struct drm_shadow_plane_state *shadow_plane_state)
 {
-	__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
-	drm_format_conv_state_init(&shadow_plane_state->fmtcnv_state);
+	if (shadow_plane_state) {
+		__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
+		drm_format_conv_state_init(&shadow_plane_state->fmtcnv_state);
+	} else {
+		__drm_atomic_helper_plane_reset(plane, NULL);
+	}
 }
 EXPORT_SYMBOL(__drm_gem_reset_shadow_plane);