From cee6d309d9edf4d2df3113d8dffe5b0382777c9c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Viktor=20S=C3=B6derqvist?= <viktor.soderqvist@est.tech>
Date: Tue, 31 Oct 2023 15:20:06 +0100
Subject: [PATCH] Don't crash when adding a forgotten node to blacklist twice
 (#12702)

Add a defensive checks to prevent double freeing a node from the cluster blacklist.

(cherry picked from commit 8d675950e6528e164454300d54aaf7bc024b075c)
---
 src/cluster.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/cluster.c b/src/cluster.c
index 0cb61d858..6b34b72c2 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -1134,6 +1134,9 @@ void clusterReset(int hard) {
     }
     dictReleaseIterator(di);
 
+    /* Empty the nodes blacklist. */
+    dictEmpty(server.cluster->nodes_black_list, NULL);
+
     /* Hard reset only: set epochs to 0, change node ID. */
     if (hard) {
         sds oldname;
@@ -2655,8 +2658,7 @@ void clusterProcessPingExtensions(clusterMsg *hdr, clusterLink *link) {
             clusterNode *n = clusterLookupNode(forgotten_node_ext->name, CLUSTER_NAMELEN);
             if (n && n != myself && !(nodeIsSlave(myself) && myself->slaveof == n)) {
                 sds id = sdsnewlen(forgotten_node_ext->name, CLUSTER_NAMELEN);
-                dictEntry *de = dictAddRaw(server.cluster->nodes_black_list, id, NULL);
-                serverAssert(de != NULL);
+                dictEntry *de = dictAddOrFind(server.cluster->nodes_black_list, id);
                 uint64_t expire = server.unixtime + ntohu64(forgotten_node_ext->ttl);
                 dictSetUnsignedIntegerVal(de, expire);
                 clusterDelNode(n);