netdev - Re: [PATCH net-next] net: phylink: fix NULL pl->pcs dereference during phylink_pcs_poll

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Message-ID: <YryrCrLyqciJqFxY@shell.armlinux.org.uk>
Date:   Wed, 29 Jun 2022 20:42:02 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Vladimir Oltean <vladimir.oltean@....com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH net-next] net: phylink: fix NULL pl->pcs dereference
 during phylink_pcs_poll_start

On Wed, Jun 29, 2022 at 10:33:58PM +0300, Vladimir Oltean wrote:
> The current link mode of the phylink instance may not require an
> attached PCS. However, phylink_major_config() unconditionally
> dereferences this potentially NULL pointer when restarting the link poll
> timer, which will panic the kernel.
> 
> Fix the problem by checking whether a PCS exists in phylink_pcs_poll_start(),
> otherwise do nothing. The code prior to the blamed patch also only
> looked at pcs->poll within an "if (pcs)" block.
> 
> Fixes: bfac8c490d60 ("net: phylink: disable PCS polling over major configuration")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

Thanks.

Reviewed-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

-- 
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