[SRU][J][PATCH] fbdev: efifb: Register sysfs groups through driver core

[Massimiliano Pellizzer]

From: Thomas Weißschuh <linux at weissschuh.net>

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 <linux at weissschuh.net>
Signed-off-by: Helge Deller <deller at gmx.de>
(backported from commit 95cdd538e0e5677efbdf8aade04ec098ab98f457)
[mpellizzer: backported considering the different return value type of
efifb_remove(), due to missing commit 156ebfe4c87d13]
CVE-2024-49925
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 drivers/video/fbdev/efifb.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
index b3d5f884c5445..f029cbe9cefb9 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -581,15 +581,10 @@ 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;
 	}
 
 	if (efifb_pci_dev)
@@ -608,8 +603,6 @@ static int efifb_probe(struct platform_device *dev)
 		pm_runtime_put(&efifb_pci_dev->dev);
 
 	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);
@@ -629,7 +622,6 @@ static int efifb_remove(struct platform_device *pdev)
 
 	/* efifb_destroy takes care of info cleanup */
 	unregister_framebuffer(info);
-	sysfs_remove_groups(&pdev->dev.kobj, efifb_groups);
 
 	return 0;
 }
@@ -637,6 +629,7 @@ static int efifb_remove(struct platform_device *pdev)
 static struct platform_driver efifb_driver = {
 	.driver = {
 		.name = "efi-framebuffer",
+		.dev_groups = efifb_groups,
 	},
 	.probe = efifb_probe,
 	.remove = efifb_remove,
-- 
2.43.0