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: <20190730033229.GA20628@lunn.ch>
Date:   Tue, 30 Jul 2019 05:32:29 +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 Tue, Jul 30, 2019 at 10:25:36AM +0800, Jia-Ju Bai wrote:
> 
> 
> On 2019/7/29 21:45, Andrew Lunn wrote:
> >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'?
> 
> Me and my colleague...

Well, we can leave it very vague, giving no idea who 'us' is. But
often you want to name the company behind it, or the university, or
the sponsor, etc.

    Andrew