[PATCH 5.14 286/432] drm/vmwgfx: fix potential UAF in vmwgfx_surface.c

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>

[ Upstream commit 2bc5da528dd570c5ecabc107e6fbdbc55974276f ]

drm_file.master should be protected by either drm_device.master_mutex
or drm_file.master_lookup_lock when being dereferenced. However,
drm_master_get is called on unprotected file_priv->master pointers in
vmw_surface_define_ioctl and vmw_gb_surface_define_internal.

This is fixed by replacing drm_master_get with drm_file_get_master.

Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210724111824.59266-4-desmondcheongzx@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index 47c03a276515..a04ad7812960 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -865,7 +865,7 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
 	user_srf->prime.base.shareable = false;
 	user_srf->prime.base.tfile = NULL;
 	if (drm_is_primary_client(file_priv))
-		user_srf->master = drm_master_get(file_priv->master);
+		user_srf->master = drm_file_get_master(file_priv);
 
 	/**
 	 * From this point, the generic resource management functions
@@ -1534,7 +1534,7 @@ vmw_gb_surface_define_internal(struct drm_device *dev,
 
 	user_srf = container_of(srf, struct vmw_user_surface, srf);
 	if (drm_is_primary_client(file_priv))
-		user_srf->master = drm_master_get(file_priv->master);
+		user_srf->master = drm_file_get_master(file_priv);
 
 	res = &user_srf->srf.res;
 
-- 
2.30.2