linux-kernel - Re: [PATCH] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change

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Message-ID: <20190729134553.GC4110@lunn.ch>
Date:   Mon, 29 Jul 2019 15:45:53 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     f.fainelli@...il.com, hkallweit1@...il.com, davem@...emloft.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: phy_led_triggers: Fix a possible null-pointer
 dereference in phy_led_trigger_change_speed()

On Mon, Jul 29, 2019 at 05:24:24PM +0800, Jia-Ju Bai wrote:
> In phy_led_trigger_change_speed(), there is an if statement on line 48
> to check whether phy->last_triggered is NULL: 
>     if (!phy->last_triggered)
> 
> When phy->last_triggered is NULL, it is used on line 52:
>     led_trigger_event(&phy->last_triggered->trigger, LED_OFF);
> 
> Thus, a possible null-pointer dereference may occur.
> 
> To fix this bug, led_trigger_event(&phy->last_triggered->trigger,
> LED_OFF) is called when phy->last_triggered is not NULL.
> 
> This bug is found by a static analysis tool STCheck written by us.

Who is 'us'? 

Thanks
    Andrew