linux-kernel - [PATCH v3] net: phy: micrel: fix crash when statistic requested for KSZ9031 phy

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Date:   Thu, 13 Apr 2017 14:11:27 -0500
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>
CC:     Sekhar Nori <nsekhar@...com>, <linux-kernel@...r.kernel.org>,
        Grygorii Strashko <grygorii.strashko@...com>
Subject: [PATCH v3] net: phy: micrel: fix crash when statistic requested for KSZ9031 phy

Now the command:
	ethtool --phy-statistics eth0
will cause system crash with meassage "Unable to handle kernel NULL pointer
dereference at virtual address 00000010" from:

 (kszphy_get_stats) from [<c069f1d8>] (ethtool_get_phy_stats+0xd8/0x210)
 (ethtool_get_phy_stats) from [<c06a0738>] (dev_ethtool+0x5b8/0x228c)
 (dev_ethtool) from [<c06b5484>] (dev_ioctl+0x3fc/0x964)
 (dev_ioctl) from [<c0679f7c>] (sock_ioctl+0x170/0x2c0)
 (sock_ioctl) from [<c02419d4>] (do_vfs_ioctl+0xa8/0x95c)
 (do_vfs_ioctl) from [<c02422c4>] (SyS_ioctl+0x3c/0x64)
 (SyS_ioctl) from [<c0107d60>] (ret_fast_syscall+0x0/0x44)

The reason: phy_driver structure for KSZ9031 phy has no .probe() callback
defined. As result, struct phy_device *phydev->priv pointer will not be
initializes (null).
This issue will affect also following phys:
 KSZ8795, KSZ886X, KSZ8873MLL, KSZ9031, KSZ9021, KSZ8061, KS8737

Fix it by:
- adding .probe() = kszphy_probe() callback to KSZ9031, KSZ9021
phys. The kszphy_probe() can be re-used as it doesn't do any phy specific
settings.
- removing statistic callbacks from other phys (KSZ8795, KSZ886X,
KSZ8873MLL, KSZ8061, KS8737) as they doesn't have corresponding
statistic counters.

Fixes: 2b2427d06426 ("phy: micrel: Add ethtool statistics counters")
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
---
changes in v3:
- occasional whitespace change removed

changes in v2:
 - probe callback added to KSZ9031, KSZ9021
 - statistic callback removed from KSZ8795, KSZ886X, KSZ8873MLL, KSZ8061, KS8737

Links
v2: https://patchwork.ozlabs.org/patch/750194/
v1: https://lkml.org/lkml/2017/4/10/1183

 drivers/net/phy/micrel.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 6742070..1326d99 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -798,9 +798,6 @@ static struct phy_driver ksphy_driver[] = {
 	.read_status	= genphy_read_status,
 	.ack_interrupt	= kszphy_ack_interrupt,
 	.config_intr	= kszphy_config_intr,
-	.get_sset_count = kszphy_get_sset_count,
-	.get_strings	= kszphy_get_strings,
-	.get_stats	= kszphy_get_stats,
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,
 }, {
@@ -940,9 +937,6 @@ static struct phy_driver ksphy_driver[] = {
 	.read_status	= genphy_read_status,
 	.ack_interrupt	= kszphy_ack_interrupt,
 	.config_intr	= kszphy_config_intr,
-	.get_sset_count = kszphy_get_sset_count,
-	.get_strings	= kszphy_get_strings,
-	.get_stats	= kszphy_get_stats,
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,
 }, {
@@ -952,6 +946,7 @@ static struct phy_driver ksphy_driver[] = {
 	.features	= PHY_GBIT_FEATURES,
 	.flags		= PHY_HAS_MAGICANEG | PHY_HAS_INTERRUPT,
 	.driver_data	= &ksz9021_type,
+	.probe		= kszphy_probe,
 	.config_init	= ksz9021_config_init,
 	.config_aneg	= genphy_config_aneg,
 	.read_status	= genphy_read_status,
@@ -971,6 +966,7 @@ static struct phy_driver ksphy_driver[] = {
 	.features	= PHY_GBIT_FEATURES,
 	.flags		= PHY_HAS_MAGICANEG | PHY_HAS_INTERRUPT,
 	.driver_data	= &ksz9021_type,
+	.probe		= kszphy_probe,
 	.config_init	= ksz9031_config_init,
 	.config_aneg	= genphy_config_aneg,
 	.read_status	= ksz9031_read_status,
@@ -989,9 +985,6 @@ static struct phy_driver ksphy_driver[] = {
 	.config_init	= kszphy_config_init,
 	.config_aneg	= ksz8873mll_config_aneg,
 	.read_status	= ksz8873mll_read_status,
-	.get_sset_count = kszphy_get_sset_count,
-	.get_strings	= kszphy_get_strings,
-	.get_stats	= kszphy_get_stats,
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,
 }, {
@@ -1003,9 +996,6 @@ static struct phy_driver ksphy_driver[] = {
 	.config_init	= kszphy_config_init,
 	.config_aneg	= genphy_config_aneg,
 	.read_status	= genphy_read_status,
-	.get_sset_count = kszphy_get_sset_count,
-	.get_strings	= kszphy_get_strings,
-	.get_stats	= kszphy_get_stats,
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,
 }, {
@@ -1017,9 +1007,6 @@ static struct phy_driver ksphy_driver[] = {
 	.config_init	= kszphy_config_init,
 	.config_aneg	= ksz8873mll_config_aneg,
 	.read_status	= ksz8873mll_read_status,
-	.get_sset_count = kszphy_get_sset_count,
-	.get_strings	= kszphy_get_strings,
-	.get_stats	= kszphy_get_stats,
 	.suspend	= genphy_suspend,
 	.resume		= genphy_resume,
 } };
-- 
2.10.1