[PATCH 4.19 29/98] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change_speed()

From: Greg Kroah-Hartman
Date: Tue Aug 27 2019 - 03:55:50 EST

[ Upstream commit 271da132e29b5341c31eca6ba6a72ea1302ebac8 ]

In phy_led_trigger_change_speed(), there is an if statement on line 48
to check whether phy->last_triggered is NULL:
if (!phy->last_triggered)

When phy->last_triggered is NULL, it is used on line 52:
led_trigger_event(&phy->last_triggered->trigger, LED_OFF);

Thus, a possible null-pointer dereference may occur.

To fix this bug, led_trigger_event(&phy->last_triggered->trigger,
LED_OFF) is called when phy->last_triggered is not NULL.

This bug is found by a static analysis tool STCheck written by
the OSLAB group in Tsinghua University.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/net/phy/phy_led_triggers.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phy_led_triggers.c b/drivers/net/phy/phy_led_triggers.c
index 491efc1bf5c48..7278eca70f9f3 100644
--- a/drivers/net/phy/phy_led_triggers.c
+++ b/drivers/net/phy/phy_led_triggers.c
@@ -58,8 +58,9 @@ void phy_led_trigger_change_speed(struct phy_device *phy)
if (!phy->last_triggered)
+ else
+ led_trigger_event(&phy->last_triggered->trigger, LED_OFF);

- led_trigger_event(&phy->last_triggered->trigger, LED_OFF);
led_trigger_event(&plt->trigger, LED_FULL);
phy->last_triggered = plt;