[PATCH AUTOSEL 5.2 070/123] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change_speed()

[Sasha Levin]

From: Jia-Ju Bai <baijiaju1...@gmail.com>

[ 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 <baijiaju1...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 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 b86a4b2116f81..59a94e07e7c55 100644
--- a/drivers/net/phy/phy_led_triggers.c
+++ b/drivers/net/phy/phy_led_triggers.c
@@ -48,8 +48,9 @@ void phy_led_trigger_change_speed(struct phy_device *phy)
                if (!phy->last_triggered)
                        led_trigger_event(&phy->led_link_trigger->trigger,
                                          LED_FULL);
+               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;
        }
-- 
2.20.1