[PATCH 6.1.y] fbdev: efifb: Register sysfs groups through driver core

[PATCH 6.1.y] fbdev: efifb: Register sysfs groups through driver core

[Xiangyu Chen]

From: Thomas Weißschuh <linux@weissschuh.net>

[ Upstream commit 95cdd538e0e5677efbdf8aade04ec098ab98f457 ]

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@weissschuh.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.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 16c1aaae9afa..53944bcc990c 100644
--- a/drivers/video/fbdev/efifb.c
+++ b/drivers/video/fbdev/efifb.c
@@ -570,15 +570,10 @@ 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)
@@ -597,8 +592,6 @@ 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);
@@ -618,7 +611,6 @@ 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;
 }
@@ -626,6 +618,7 @@ 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

Re: [PATCH 6.1.y] fbdev: efifb: Register sysfs groups through driver core

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 95cdd538e0e5677efbdf8aade04ec098ab98f457

WARNING: Author mismatch between patch and upstream commit:
Backport author: Xiangyu Chen <xiangyu.chen@eng.windriver.com>
Commit author: Thomas Weißschuh <linux@weissschuh.net>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.11.y | Present (different SHA1: 4684d69b9670)
6.6.y | Present (different SHA1: 36bfefb6baaa)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
--- -	2024-11-25 21:40:25.872982840 -0500
+++ /tmp/tmp.oieDEbdQgp	2024-11-25 21:40:25.860889130 -0500
@@ -1,3 +1,5 @@
+[ Upstream commit 95cdd538e0e5677efbdf8aade04ec098ab98f457 ]
+
 The driver core can register and cleanup sysfs groups already.
 Make use of that functionality to simplify the error handling and
 cleanup.
@@ -7,15 +9,17 @@
 
 Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
 Signed-off-by: Helge Deller <deller@gmx.de>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.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 8dd82afb3452b..595b8e27bea66 100644
+index 16c1aaae9afa..53944bcc990c 100644
 --- a/drivers/video/fbdev/efifb.c
 +++ b/drivers/video/fbdev/efifb.c
-@@ -561,15 +561,10 @@ static int efifb_probe(struct platform_device *dev)
+@@ -570,15 +570,10 @@ static int efifb_probe(struct platform_device *dev)
  		break;
  	}
  
@@ -31,27 +35,32 @@
 +		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)
+ 	if (efifb_pci_dev)
+@@ -597,8 +592,6 @@ static int efifb_probe(struct platform_device *dev)
+ 		pm_runtime_put(&efifb_pci_dev->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)
+@@ -618,7 +611,6 @@ 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;
+ }
+@@ -626,6 +618,7 @@ 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_new = efifb_remove,
+ 	.remove = efifb_remove,
+-- 
+2.43.0
+
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |