Patch "drm/sysfb: Do not dereference NULL pointer in plane reset" has been added to the 6.17-stable tree

Patch "drm/sysfb: Do not dereference NULL pointer in plane reset" has been added to the 6.17-stable tree

[gregkh]

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

    drm/sysfb: Do not dereference NULL pointer in plane reset

to the 6.17-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-sysfb-do-not-dereference-null-pointer-in-plane-reset.patch
and it can be found in the queue-6.17 subdirectory.

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


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: drm/sysfb: Do not dereference NULL pointer in plane reset

From: Thomas Zimmermann <tzimmermann@suse.de>

commit 14e02ed3876f4ab0ed6d3f41972175f8b8df3d70 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/drm_gem_atomic_helper.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- 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_pla
 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);
 


Patches currently in stable-queue which might be from tzimmermann@suse.de are

queue-6.17/drm-ast-clear-preserved-bits-from-register-output-value.patch
queue-6.17/fbcon-set-fb_display-mode-to-null-when-the-mode-is-released.patch
queue-6.17/drm-sysfb-do-not-dereference-null-pointer-in-plane-reset.patch
queue-6.17/fbdev-bitblit-bound-check-glyph-index-in-bit_putcs.patch