linux-kernel - Re: net: phy: realtek: regression, kernel null pointer dereference

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Message-ID: <11446b0b-c8a4-4e5f-bfa0-0892b500f467@gmail.com>
Date:   Sat, 11 May 2019 16:46:40 +0200
From:   Vicente Bergas <vicencb@...il.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: net: phy: realtek: regression, kernel null pointer dereference

On Friday, May 10, 2019 10:28:06 PM CEST, Heiner Kallweit wrote:
> On 10.05.2019 17:05, Vicente Bergas wrote:
>> Hello,
>> there is a regression on linux v5.1-9573-gb970afcfcabd with a kernel null
>> pointer dereference.
>> The issue is the commit f81dadbcf7fd067baf184b63c179fc392bdb226e
>>  net: phy: realtek: Add rtl8211e rx/tx delays config ...
> The page operation callbacks are missing in the RTL8211E driver.
> I just submitted a fix adding these callbacks to few Realtek PHY drivers
> including RTl8211E. This should fix the issue.

Hello Heiner,
just tried your patch and indeed the NPE is gone. But still no network...
The MAC <-> PHY link was working before, so, maybe the rgmii delays are not
correctly configured.
With this change it is back to working:
--- a/drivers/net/phy/realtek.c
+++ b/drivers/net/phy/realtek.c
@@ -300,7 +300,6 @@
 	}, {
 		PHY_ID_MATCH_EXACT(0x001cc915),
 		.name		= "RTL8211E Gigabit Ethernet",
-		.config_init	= &rtl8211e_config_init,
 		.ack_interrupt	= &rtl821x_ack_interrupt,
 		.config_intr	= &rtl8211e_config_intr,
 		.suspend	= genphy_suspend,
That is basically reverting the patch.

Regards,
  Vicenç.

> Nevertheless your proposed patch looks good to me, just one small change
> would be needed and it should be splitted.
>
> The change to phy-core I would consider a fix and it should be fine to
> submit it to net (net-next is closed currently).
>
> Adding the warning to the Realtek driver is fine, but this would be
> something for net-next once it's open again.
>
>> Regards,
>>  Vicenç.
>> 
> Heiner
>
>> --- a/drivers/net/phy/phy-core.c
>> +++ b/drivers/net/phy/phy-core.c
>> @@ -648,11 +648,17 @@
>> 
>> static int __phy_read_page(struct phy_device *phydev)
>> { ...
>
> Here phydev_warn() should be used.
>
>> +        return 0;
>> +    }
>> 
>>     ret = phy_write(phydev, RTL821x_EXT_PAGE_SELECT, 0xa4);
>>     if (ret)