linux-kernel - Re: [PATCH] NFC: Fix error handling in nfc_genl_dump

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Message-ID: <20251214135440.51409316@pumpkin>
Date: Sun, 14 Dec 2025 13:54:40 +0000
From: David Laight <david.laight.linux@...il.com>
To: Ma Ke <make24@...as.ac.cn>
Cc: krzk@...nel.org, davem@...emloft.net, edumazet@...gle.com,
 kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
 aloisio.almeida@...nbossa.org, lauro.venancio@...nbossa.org,
 sameo@...ux.intel.com, linville@...driver.com, johannes@...solutions.net,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 akpm@...ux-foundation.org, stable@...r.kernel.org
Subject: Re: [PATCH] NFC: Fix error handling in nfc_genl_dump_targets

On Sun, 14 Dec 2025 21:17:26 +0800
Ma Ke <make24@...as.ac.cn> wrote:

> nfc_genl_dump_targets() increments the device reference count via
> nfc_get_device() but fails to decrement it properly. nfc_get_device()
> calls class_find_device() which internally calls get_device() to
> increment the reference count. No corresponding put_device() is made
> to decrement the reference count.
> 
> Add proper reference count decrementing using nfc_put_device() when
> the dump operation completes or encounters an error, ensuring balanced
> reference counting.
> 
> Found by code review.

Is that some half-hearted AI code review?

Isn't the 'put' done by nfc_genl_dump_targets_done() which it looks
like the outer code calls sometime later on.

	David

> 
> Cc: stable@...r.kernel.org
> Fixes: 4d12b8b129f1 ("NFC: add nfc generic netlink interface")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
>  net/nfc/netlink.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/nfc/netlink.c b/net/nfc/netlink.c
> index a18e2c503da6..9ae138ee91dd 100644
> --- a/net/nfc/netlink.c
> +++ b/net/nfc/netlink.c
> @@ -159,6 +159,11 @@ static int nfc_genl_dump_targets(struct sk_buff *skb,
>  
>  	cb->args[0] = i;
>  
> +	if (rc < 0 || i >= dev->n_targets) {
> +		nfc_put_device(dev);
> +		cb->args[1] = 0;
> +	}
> +
>  	return skb->len;
>  }
>