[PATCH net v5 6/6] net: phy: avoid double-free after LED trigger registration failure

[Xuanqiang Luo]

From: Xuanqiang Luo <luoxuanqiang@xxxxxxxxxx>

phy_led_triggers_register() frees phy_led_triggers when a speed trigger
registration fails, but leaves the pointer set to the freed allocation
before clearing phy_num_led_triggers.

phy_probe() ignores the registration error. If a later probe step fails,
its error path calls phy_led_triggers_unregister(); normal teardown during
an unbind or MDIO bus removal calls the same helper from phy_remove().
In either case, the trigger count is zero, so the per-trigger unregister
loop is skipped, but the dangling pointer is still freed unconditionally.

Clear the pointer when partial registration cleanup frees the array, and
make phy_led_triggers_unregister() free the array only when its pointer is
non-NULL.

Fixes: b7f0ee992adf ("net: phy: leds: fix memory leak")
Signed-off-by: Xuanqiang Luo <luoxuanqiang@xxxxxxxxxx>
---
 drivers/net/phy/phy_led_triggers.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/phy_led_triggers.c b/drivers/net/phy/phy_led_triggers.c
index 4eb7716bb9d6c..ff6e518395be0 100644
--- a/drivers/net/phy/phy_led_triggers.c
+++ b/drivers/net/phy/phy_led_triggers.c
@@ -126,6 +126,7 @@ int phy_led_triggers_register(struct phy_device *phy)
 	while (i--)
 		phy_led_trigger_unregister(&phy->phy_led_triggers[i]);
 	kfree(phy->phy_led_triggers);
+	phy->phy_led_triggers = NULL;
 out_unreg_link:
 	phy_led_trigger_unregister(phy->led_link_trigger);
 out_free_link:
@@ -141,10 +142,12 @@ void phy_led_triggers_unregister(struct phy_device *phy)
 {
 	int i;
 
-	for (i = 0; i < phy->phy_num_led_triggers; i++)
-		phy_led_trigger_unregister(&phy->phy_led_triggers[i]);
-	kfree(phy->phy_led_triggers);
-	phy->phy_led_triggers = NULL;
+	if (phy->phy_led_triggers) {
+		for (i = 0; i < phy->phy_num_led_triggers; i++)
+			phy_led_trigger_unregister(&phy->phy_led_triggers[i]);
+		kfree(phy->phy_led_triggers);
+		phy->phy_led_triggers = NULL;
+	}
 
 	if (phy->led_link_trigger) {
 		phy_led_trigger_unregister(phy->led_link_trigger);
-- 
2.43.0