From 531dc03960058ebf72e593f3ae36d99db4d1af17 Mon Sep 17 00:00:00 2001
From: Daniele Lacamera <dan@danielinux.net>
Date: Tue, 5 Sep 2023 21:59:41 +0200
Subject: [PATCH] Fix null pointer dereference in IGMP

---
 modules/pico_igmp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/modules/pico_igmp.c b/modules/pico_igmp.c
index bf20ad78..ade4b5b3 100644
--- a/modules/pico_igmp.c
+++ b/modules/pico_igmp.c
@@ -367,6 +367,8 @@ static int pico_igmp_timer_is_running(struct igmp_timer *t)
     test.type = t->type;
     test.mcast_link = t->mcast_link;
     test.mcast_group = t->mcast_group;
+    if (!t->stack)
+        return 0;
     timer = pico_tree_findKey(&t->stack->IGMPTimers, &test);
     if (timer)
         return 1;