[PATCH net v4 6/6] net: phy: avoid double-free after LED trigger registration failure

[Xuanqiang Luo <xuanqiang.luo@linux.dev>]

From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

When a speed trigger registration fails, phy_led_triggers_register() frees
phy_led_triggers but leaves the pointer set to the freed allocation. It
then clears phy_num_led_triggers.

phy_probe() ignores this error. If device-tree LED setup then fails, its
error path calls phy_led_triggers_unregister(). The zero trigger count
skips the per-trigger unregister loop, but the helper still frees the
dangling pointer.

Clear the pointer after partial registration cleanup and make
phy_led_triggers_unregister() walk and free the array only while it is
present.

Fixes: b7f0ee992adf ("net: phy: leds: fix memory leak")
Signed-off-by: Xuanqiang Luo <luoxuanqiang@kylinos.cn>
---
 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