linux-kernel - [PATCH][next] drm/kmb: Fix dereference of pointer plane before a null check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250730133457.2076784-1-colin.i.king@gmail.com>
Date: Wed, 30 Jul 2025 14:34:57 +0100
From: Colin Ian King <colin.i.king@...il.com>
To: Anitha Chrisanthus <anitha.chrisanthus@...el.com>,
	Edmund Dea <edmund.j.dea@...el.com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Maxime Ripard <mripard@...nel.org>,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	dri-devel@...ts.freedesktop.org
Cc: kernel-janitors@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH][next] drm/kmb: Fix dereference of pointer plane before a null check

Currently pointer plane is being dereferenced on the calls to
drm_atomic_get_old_plane_state and drm_atomic_get_new_plane_state
when assigning old_plane_state and new_plane_state, this could
lead to a null pointer dereference. Fix this by first performing
a null pointer check on plane, then assigning old_plane_state and
new_plance_state and then null pointer checking these.

Fixes: 977697e20b3d ("drm/atomic: Pass the full state to planes atomic disable and update")
Fixes: 37418bf14c13 ("drm: Use state helper instead of the plane state pointer")

Signed-off-by: Colin Ian King <colin.i.king@...il.com>
---
 drivers/gpu/drm/kmb/kmb_plane.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/kmb/kmb_plane.c b/drivers/gpu/drm/kmb/kmb_plane.c
index 9e0562aa2bcb..07498deba1b6 100644
--- a/drivers/gpu/drm/kmb/kmb_plane.c
+++ b/drivers/gpu/drm/kmb/kmb_plane.c
@@ -341,10 +341,8 @@ static void kmb_plane_set_alpha(struct kmb_drm_private *kmb,
 static void kmb_plane_atomic_update(struct drm_plane *plane,
 				    struct drm_atomic_state *state)
 {
-	struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state,
-										 plane);
-	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
-										 plane);
+	struct drm_plane_state *old_plane_state;
+	struct drm_plane_state *new_plane_state;
 	struct drm_framebuffer *fb;
 	struct kmb_drm_private *kmb;
 	unsigned int width;
@@ -359,7 +357,12 @@ static void kmb_plane_atomic_update(struct drm_plane *plane,
 	static dma_addr_t addr[MAX_SUB_PLANES];
 	struct disp_cfg *init_disp_cfg;
 
-	if (!plane || !new_plane_state || !old_plane_state)
+	if (!plane)
+		return;
+
+	old_plane_state = drm_atomic_get_old_plane_state(state, plane);
+	new_plane_state = drm_atomic_get_new_plane_state(state, plane);
+	if (!old_plane_state || !new_plane_state)
 		return;
 
 	fb = new_plane_state->fb;
-- 
2.50.0