[PATCH 5.14 351/849] net: phylink: dont call netif_carrier_off() with NULL netdev

Greg Kroah-Hartman
2021-11-16T01:35:55Z

From: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

[ Upstream commit cbcca2e3961eac736566ac13ef0d0bf6f0b764ec ]

Dan Carpenter points out that we have a code path that permits a NULL
netdev pointer to be passed to netif_carrier_off(), which will cause
a kernel oops. In any case, we need to set pl->old_link_state to false
to have the desired effect when there is no netdev present.

Fixes: f97493657c63 ("net: phylink: add suspend/resume support")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/phy/phylink.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 0d3d9c3ee83c8..6e96d7b7ee445 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1332,7 +1332,10 @@ void phylink_suspend(struct phylink *pl, bool mac_wol)
* but one would hope all packets have been sent. This
* also means phylink_resolve() will do nothing.
*/
- netif_carrier_off(pl->netdev);
+ if (pl->netdev)
+ netif_carrier_off(pl->netdev);
+ else
+ pl->old_link_state = false;

/* We do not call mac_link_down() here as we want the
* link to remain up to receive the WoL packets.
--
2.33.0