drm/vmwgfx: Limit the user-space command buffer size

With older hardware versions, the user could specify arbitrarily large
command buffer sizes, causing a vmalloc / vmap space exhaustion.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Sinclair Yeh <syeh@vmware.com>
Cc: stable@vger.kernel.org

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index ddd5e8a59723..d1f4a48dee0f 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -3891,14 +3891,14 @@ static void *vmw_execbuf_cmdbuf(struct vmw_private *dev_priv,
         int ret;
 
         *header = NULL;
-        if (!dev_priv->cman || kernel_commands)
-                return kernel_commands;
-
         if (command_size > SVGA_CB_MAX_SIZE) {
                 DRM_ERROR("Command buffer is too large.\n");
                 return ERR_PTR(-EINVAL);
         }
 
+        if (!dev_priv->cman || kernel_commands)
+                return kernel_commands;
+
         /* If possible, add a little space for fencing. */
         cmdbuf_size = command_size + 512;
         cmdbuf_size = min_t(size_t, cmdbuf_size, SVGA_CB_MAX_SIZE);