[PATCH AUTOSEL 5.15 09/10] drm/vmwgfx: Limit display layout ioctl array size to VMWGFX_NUM_DISPLAY_UNITS

[Sasha Levin <sashal@kernel.org>]

From: Ian Forbes <ian.forbes@broadcom.com>

[ Upstream commit 28a5dfd4f615539fb22fb6d5c219c199c14e6eb6 ]

Currently the array size is only limited by the largest kmalloc size which
is incorrect. This change will also return a more specific error message
than ENOMEM to userspace.

Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com>
Reviewed-by: Martin Krastev <martin.krastev@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240808200634.1074083-1-ian.forbes@broadcom.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 4 ++--
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 4 +++-
 drivers/gpu/drm/vmwgfx/vmwgfx_kms.h | 3 ---
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 7bb7a69321d30..9c60bb2aefe1f 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -59,7 +59,7 @@
 #define VMWGFX_DRIVER_MINOR 19
 #define VMWGFX_DRIVER_PATCHLEVEL 0
 #define VMWGFX_FIFO_STATIC_SIZE (1024*1024)
-#define VMWGFX_MAX_DISPLAYS 16
+#define VMWGFX_NUM_DISPLAY_UNITS 8
 #define VMWGFX_CMD_BOUNCE_INIT_SIZE 32768
 
 #define VMWGFX_PCI_ID_SVGA2              0x0405
@@ -71,7 +71,7 @@
 #define VMWGFX_NUM_GB_CONTEXT 256
 #define VMWGFX_NUM_GB_SHADER 20000
 #define VMWGFX_NUM_GB_SURFACE 32768
-#define VMWGFX_NUM_GB_SCREEN_TARGET VMWGFX_MAX_DISPLAYS
+#define VMWGFX_NUM_GB_SCREEN_TARGET VMWGFX_NUM_DISPLAY_UNITS
 #define VMWGFX_NUM_DXCONTEXT 256
 #define VMWGFX_NUM_DXQUERY 512
 #define VMWGFX_NUM_MOB (VMWGFX_NUM_GB_CONTEXT +\
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index e2a52b5de1733..736e3252c6b5d 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2294,7 +2294,7 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data,
 	struct drm_mode_config *mode_config = &dev->mode_config;
 	struct drm_vmw_update_layout_arg *arg =
 		(struct drm_vmw_update_layout_arg *)data;
-	void __user *user_rects;
+	const void __user *user_rects;
 	struct drm_vmw_rect *rects;
 	struct drm_rect *drm_rects;
 	unsigned rects_size;
@@ -2307,6 +2307,8 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data,
 			      def_rect.x2, def_rect.y2);
 		vmw_du_update_layout(dev_priv, 1, &def_rect);
 		return 0;
+	} else if (arg->num_outputs > VMWGFX_NUM_DISPLAY_UNITS) {
+		return -E2BIG;
 	}
 
 	rects_size = arg->num_outputs * sizeof(struct drm_vmw_rect);
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
index 23c2dc943caf0..85595d0bcfcec 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h
@@ -198,9 +198,6 @@ struct vmw_kms_dirty {
 	s32 unit_y2;
 };
 
-#define VMWGFX_NUM_DISPLAY_UNITS 8
-
-
 #define vmw_framebuffer_to_vfb(x) \
 	container_of(x, struct vmw_framebuffer, base)
 #define vmw_framebuffer_to_vfbs(x) \
-- 
2.43.0