2019-07-30 14:50:33

by Jia-Ju Bai

Subject: [PATCH v2] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change_speed()

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 <[email protected]>
---
v2:
* Add the organization of the tool's authors.
Thank David and Andrew for helpful advice.

---
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 b86a4b2116f8..59a94e07e7c5 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;
}
--
2.17.0

2019-08-01 00:04:57

by David Miller

Subject: Re: [PATCH v2] net: phy: phy_led_triggers: Fix a possible null-pointer dereference in phy_led_trigger_change_speed()

From: Jia-Ju Bai <[email protected]>
Date: Tue, 30 Jul 2019 16:08:13 +0800

> 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 <[email protected]>

Applied, thanks.