Re: [PATCH V2] software node: Prevent link creation failure from causing kobj reference count imbalance

[Andy Shevchenko]

On Mon, Apr 14, 2025 at 03:11:23PM +0800, Lizhi Xu wrote:
> syzbot reported a uaf in software_node_notify_remove. [1]
> 
> When any of the two sysfs_create_link() in software_node_notify() fails,
> the swnode->kobj reference count will not increase normally, which will
> cause swnode to be released incorrectly due to the imbalance of kobj reference
> count when executing software_node_notify_remove().
> 
> Increase the reference count of kobj before creating the link to avoid uaf.
> 
> [1]
> BUG: KASAN: slab-use-after-free in software_node_notify_remove+0x1bc/0x1c0 drivers/base/swnode.c:1108
> Read of size 1 at addr ffff888033c08908 by task syz-executor105/5844
> Freed by task 5844:
>  software_node_notify_remove+0x159/0x1c0 drivers/base/swnode.c:1106
>  device_platform_notify_remove drivers/base/core.c:2387 [inline]

The fix looks correct to me,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

-- 
With Best Regards,
Andy Shevchenko