linux-kernel - [PATCH] drm/nouveau: check ioctl command codes better

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Message-Id: <20250711072458.2665325-1-arnd@kernel.org>
Date: Fri, 11 Jul 2025 09:24:53 +0200
From: Arnd Bergmann <arnd@...nel.org>
To: Lyude Paul <lyude@...hat.com>,
	Danilo Krummrich <dakr@...nel.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Ben Skeggs <bskeggs@...hat.com>
Cc: Arnd Bergmann <arnd@...db.de>,
	Ben Skeggs <bskeggs@...dia.com>,
	Timur Tabi <ttabi@...dia.com>,
	Dave Airlie <airlied@...hat.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	dri-devel@...ts.freedesktop.org,
	nouveau@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/nouveau: check ioctl command codes better

From: Arnd Bergmann <arnd@...db.de>

nouveau_drm_ioctl() only checks the _IOC_NR() bits in the DRM_NOUVEAU_NVIF
command, but ignores the type and direction bits, so any command with
'7' in the low eight bits gets passed into nouveau_abi16_ioctl() instead
of drm_ioctl().

Check for all the bits except the size that is handled inside of the handler.

Fixes: 27111a23d01c ("drm/nouveau: expose the full object/event interfaces to userspace")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/nouveau/nouveau_drm.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index 1527b801f013..506eeb44f0d4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -1284,6 +1284,9 @@ nouveau_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(NOUVEAU_EXEC, nouveau_exec_ioctl_exec, DRM_RENDER_ALLOW),
 };
 
+#define DRM_IOCTL_NOUVEAU_NVIV _IOC(_IOC_READ|_IOC_WRITE, DRM_IOCTL_BASE, \
+				    DRM_COMMAND_BASE + DRM_NOUVEAU_NVIF, 0)
+
 long
 nouveau_drm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
@@ -1297,14 +1300,10 @@ nouveau_drm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		return ret;
 	}
 
-	switch (_IOC_NR(cmd) - DRM_COMMAND_BASE) {
-	case DRM_NOUVEAU_NVIF:
+	if ((cmd & ~IOCSIZE_MASK) == DRM_IOCTL_NOUVEAU_NVIV)
 		ret = nouveau_abi16_ioctl(filp, (void __user *)arg, _IOC_SIZE(cmd));
-		break;
-	default:
+	else
 		ret = drm_ioctl(file, cmd, arg);
-		break;
-	}
 
 	pm_runtime_mark_last_busy(dev->dev);
 	pm_runtime_put_autosuspend(dev->dev);
-- 
2.39.5