fbdev: efifb: Register sysfs groups through driver core

The driver core can register and cleanup sysfs groups already.
Make use of that functionality to simplify the error handling and
cleanup.

Also avoid a UAF race during unregistering where the sysctl attributes
were usable after the info struct was freed.

Signed-off-by: Thomas Weißschuh <[email protected]>
Signed-off-by: Helge Deller <[email protected]>

Author: t-8ch

drivers/video/fbdev/efifb.c

@@ -561,15 +561,10 @@ static int efifb_probe(struct platform_device *dev)
 		break;
 	}
 
-	err = sysfs_create_groups(&dev->dev.kobj, efifb_groups);
-	if (err) {
-		pr_err("efifb: cannot add sysfs attrs\n");
-		goto err_unmap;
-	}
 	err = fb_alloc_cmap(&info->cmap, 256, 0);
 	if (err < 0) {
 		pr_err("efifb: cannot allocate colormap\n");
-		goto err_groups;
+		goto err_unmap;
 	}
 
 	err = devm_aperture_acquire_for_platform_device(dev, par->base, par->size);
@@ -587,8 +582,6 @@ static int efifb_probe(struct platform_device *dev)
 
 err_fb_dealloc_cmap:
 	fb_dealloc_cmap(&info->cmap);
-err_groups:
-	sysfs_remove_groups(&dev->dev.kobj, efifb_groups);
 err_unmap:
 	if (mem_flags & (EFI_MEMORY_UC | EFI_MEMORY_WC))
 		iounmap(info->screen_base);
@@ -608,12 +601,12 @@ static void efifb_remove(struct platform_device *pdev)
 
 	/* efifb_destroy takes care of info cleanup */
 	unregister_framebuffer(info);
-	sysfs_remove_groups(&pdev->dev.kobj, efifb_groups);
 }
 
 static struct platform_driver efifb_driver = {
 	.driver = {
 		.name = "efi-framebuffer",
+		.dev_groups = efifb_groups,
 	},
 	.probe = efifb_probe,
 	.remove_new = efifb_remove,