linux-kernel - [PATCH AUTOSEL 5.10 100/176] drm/vmwgfx: fix potential UAF in vmwgfx

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Date:   Thu,  9 Sep 2021 07:50:02 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Desmond Cheong Zhi Xi <desmondcheongzx@...il.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Zack Rusin <zackr@...are.com>, Sasha Levin <sashal@...nel.org>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.10 100/176] drm/vmwgfx: fix potential UAF in vmwgfx_surface.c

From: Desmond Cheong Zhi Xi <desmondcheongzx@...il.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@...il.com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
Reviewed-by: Zack Rusin <zackr@...are.com>
Signed-off-by: Zack Rusin <zackr@...are.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210724111824.59266-4-desmondcheongzx@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.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 f493b20c7a38..f1a51371de5b 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -866,7 +866,7 @@ 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
@@ -1537,7 +1537,7 @@ 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);
 
 	ret = ttm_read_lock(&dev_priv->reservation_sem, true);
 	if (unlikely(ret != 0))
-- 
2.30.2