linux-kernel - Re: [PATCH] net-sysfs: fix error handling in netdev_register

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Message-ID: <2025031355-legend-liftoff-63bc@gregkh>
Date: Thu, 13 Mar 2025 10:58:17 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Ma Ke <make24@...as.ac.cn>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, horms@...nel.org, jdamato@...tly.com,
	aleksander.lobakin@...el.com, quic_zijuhu@...cinc.com,
	andriy.shevchenko@...ux.intel.com, wanghai26@...wei.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH] net-sysfs: fix error handling in
 netdev_register_kobject()

On Thu, Mar 13, 2025 at 03:55:28PM +0800, Ma Ke wrote:
> Once device_add() failed, we should call put_device() to decrement
> reference count for cleanup. Or it could cause memory leak.
> 
> As comment of device_add() says, 'if device_add() succeeds, you should
> call device_del() when you want to get rid of it. If device_add() has
> not succeeded, use only put_device() to drop the reference count'.
> 
> Found by code review.
> 
> Cc: stable@...r.kernel.org
> Fixes: 8ed633b9baf9 ("Revert "net-sysfs: Fix memory leak in netdev_register_kobject"")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
>  net/core/net-sysfs.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 07cb99b114bd..f443eacc9237 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -2169,6 +2169,7 @@ int netdev_register_kobject(struct net_device *ndev)
>  
>  	error = device_add(dev);
>  	if (error)
> +		put_device(dev);
>  		return error;

You obviously did not test this :(

Please be more careful in the future.