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Date: Thu, 11 Jun 2026 17:11:02 +0100
From: Simon Horman <horms@kernel.org>
To: Wentao Liang <vulab@iscas.ac.cn>
Cc: nbd@nbd.name, lorenzo@kernel.org, andrew+netdev@lunn.ch,
	davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, matthias.bgg@gmail.com,
	angelogioacchino.delregno@collabora.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, stable@vger.kernel.org
Subject: Re: [PATCH] net: ethernet: mediatek: fix refcount leak in mtk_probe()
Message-ID: <20260611161102.GV3920875@horms.kernel.org>
References: <20260609081300.208168-1-vulab@iscas.ac.cn>
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In-Reply-To: <20260609081300.208168-1-vulab@iscas.ac.cn>

On Tue, Jun 09, 2026 at 08:13:00AM +0000, Wentao Liang wrote:
> If mtk_sgmii_init() fails after successfully creating some PCS
> instances, it returns an error without cleaning up the partially
> created ones.  mtk_pcs_lynxi_create() increments the fwnode
> refcount for each PCS it creates, but this refcount is never
> released because mtk_probe() uses a plain "return err" instead of
> a goto to the err_destroy_sgmii label.  This leaks both the PCS
> devices and their fwnode references.
> 
> Fix the leak by jumping to the existing err_destroy_sgmii path
> which calls mtk_sgmii_destroy() to safely release all allocated
> resources.
> 
> Cc: stable@vger.kernel.org
> Fixes: 9ffee4a8276c ("net: ethernet: mediatek: Extend SGMII related functions")
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>

I think that a better approach would be, on error, for mtk_sgmii_init()
to release any resources it has allocated before returning.

Also, I'm not convinced this is stable material
as I'm not sure it's bothering anyone.

...