[PATCH 5.10 065/122] lan743x: fix for potential NULL pointer dereference with bare card

Greg Kroah-Hartman
2024-02-27T14:28:28Z

From: Sergej Bauer <sbauer@blackbox.su>

[ Upstream commit e9e13b6adc338be1eb88db87bcb392696144bd02 ]

This is the 3rd revision of the patch fix for potential null pointer dereference
with lan743x card.

The simpliest way to reproduce: boot with bare lan743x and issue "ethtool ethN"
commant where ethN is the interface with lan743x card. Example:

$ sudo ethtool eth7
dmesg:
[ 103.510336] BUG: kernel NULL pointer dereference, address: 0000000000000340
...
[ 103.510836] RIP: 0010:phy_ethtool_get_wol+0x5/0x30 [libphy]
...
[ 103.511629] Call Trace:
[ 103.511666] lan743x_ethtool_get_wol+0x21/0x40 [lan743x]
[ 103.511724] dev_ethtool+0x1507/0x29d0
[ 103.511769] ? avc_has_extended_perms+0x17f/0x440
[ 103.511820] ? tomoyo_init_request_info+0x84/0x90
[ 103.511870] ? tomoyo_path_number_perm+0x68/0x1e0
[ 103.511919] ? tty_insert_flip_string_fixed_flag+0x82/0xe0
[ 103.511973] ? inet_ioctl+0x187/0x1d0
[ 103.512016] dev_ioctl+0xb5/0x560
[ 103.512055] sock_do_ioctl+0xa0/0x140
[ 103.512098] sock_ioctl+0x2cb/0x3c0
[ 103.512139] __x64_sys_ioctl+0x84/0xc0
[ 103.512183] do_syscall_64+0x33/0x80
[ 103.512224] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 103.512274] RIP: 0033:0x7f54a9cba427
...

Previous versions can be found at:
v1:
initial version
https://lkml.org/lkml/2020/10/28/921

v2:
do not return from lan743x_ethtool_set_wol if netdev->phydev == NULL, just skip
the call of phy_ethtool_set_wol() instead.
https://lkml.org/lkml/2020/10/31/380

v3:
in function lan743x_ethtool_set_wol:
use ternary operator instead of if-else sentence (review by Markus Elfring)
return -ENETDOWN insted of -EIO (review by Andrew Lunn)

Signed-off-by: Sergej Bauer <sbauer@blackbox.su>

Link: https://lore.kernel.org/r/20201101223556.16116-1-sbauer@blackbox.su
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/microchip/lan743x_ethtool.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_ethtool.c b/drivers/net/ethernet/microchip/lan743x_ethtool.c
index dcde496da7fb4..c5de8f46cdd35 100644
--- a/drivers/net/ethernet/microchip/lan743x_ethtool.c
+++ b/drivers/net/ethernet/microchip/lan743x_ethtool.c
@@ -780,7 +780,9 @@ static void lan743x_ethtool_get_wol(struct net_device *netdev,

wol->supported = 0;
wol->wolopts = 0;
- phy_ethtool_get_wol(netdev->phydev, wol);
+
+ if (netdev->phydev)
+ phy_ethtool_get_wol(netdev->phydev, wol);

wol->supported |= WAKE_BCAST | WAKE_UCAST | WAKE_MCAST |
WAKE_MAGIC | WAKE_PHY | WAKE_ARP;
@@ -809,9 +811,8 @@ static int lan743x_ethtool_set_wol(struct net_device *netdev,

device_set_wakeup_enable(&adapter->pdev->dev, (bool)wol->wolopts);

- phy_ethtool_set_wol(netdev->phydev, wol);
-
- return 0;
+ return netdev->phydev ? phy_ethtool_set_wol(netdev->phydev, wol)
+ : -ENETDOWN;
}
#endif /* CONFIG_PM */

--
2.43.0