linux-kernel - Re: [PATCH net] net: phy: leds: fix memory leak

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Message-ID: <f9f60754-ef84-483f-bd77-b7bc99aadb27@lunn.ch>
Date: Thu, 17 Apr 2025 15:55:00 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Qingfang Deng <dqfext@...il.com>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"Maciej S. Szmigiero" <mail@...iej.szmigiero.name>,
	Nathan Sullivan <nathan.sullivan@...com>,
	Josh Cartwright <josh.cartwright@...com>,
	Zach Brown <zach.brown@...com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Chuanhong Guo <gch981213@...il.com>,
	Qingfang Deng <qingfang.deng@...lower.com.cn>,
	Hao Guan <hao.guan@...lower.com.cn>
Subject: Re: [PATCH net] net: phy: leds: fix memory leak

On Thu, Apr 17, 2025 at 11:25:56AM +0800, Qingfang Deng wrote:
> From: Qingfang Deng <qingfang.deng@...lower.com.cn>
> 
> A network restart test on a router led to an out-of-memory condition,
> which was traced to a memory leak in the PHY LED trigger code.
> 
> The root cause is misuse of the devm API. The registration function
> (phy_led_triggers_register) is called from phy_attach_direct, not
> phy_probe, and the unregister function (phy_led_triggers_unregister)
> is called from phy_detach, not phy_remove. This means the register and
> unregister functions can be called multiple times for the same PHY
> device, but devm-allocated memory is not freed until the driver is
> unbound.
> 
> This also prevents kmemleak from detecting the leak, as the devm API
> internally stores the allocated pointer.
> 
> Fix this by replacing devm_kzalloc/devm_kcalloc with standard
> kzalloc/kcalloc, and add the corresponding kfree calls in the unregister
> path.
> 
> Fixes: 3928ee6485a3 ("net: phy: leds: Add support for "link" trigger")
> Fixes: 2e0bc452f472 ("net: phy: leds: add support for led triggers on phy link state change")
> Signed-off-by: Hao Guan <hao.guan@...lower.com.cn>
> Signed-off-by: Qingfang Deng <qingfang.deng@...lower.com.cn>

Thanks for the fix. I agree with Maxime, this looks correct.

Reviewed-by: Andrew Lunn <andrew@...n.ch>

The use of devm_free() should trigger any reviewer to take a closer
look because it generally means something is wrong.

    Andrew