From: Ed Kellett <redacted>
Date: Wed, 19 May 2021 13:44:55 +0000 (+0100)
Subject: msgbuf_cache_get: Don't create cycle when evicting
X-Git-Url: https://jfr.im/git/solanum.git/commitdiff_plain/888d20da6d178e734ad5a2f938dc4f6966927feb

msgbuf_cache_get: Don't create cycle when evicting
---

diff --git a/ircd/msgbuf.c b/ircd/msgbuf.c
index 46bf88af..a801ff62 100644
--- a/ircd/msgbuf.c
+++ b/ircd/msgbuf.c
@@ -440,6 +440,7 @@ msgbuf_cache_get(struct MsgBuf_cache *cache, unsigned int caps)
 	struct MsgBuf_cache_entry *entry = cache->head;
 	struct MsgBuf_cache_entry *prev = NULL;
 	struct MsgBuf_cache_entry *result = NULL;
+	struct MsgBuf_cache_entry *tail = NULL;
 	int n = 0;
 
 	while (entry != NULL) {
@@ -449,6 +450,7 @@ msgbuf_cache_get(struct MsgBuf_cache *cache, unsigned int caps)
 			break;
 		}
 
+		tail = prev;
 		prev = entry;
 		entry = entry->next;
 		n++;
@@ -462,6 +464,8 @@ msgbuf_cache_get(struct MsgBuf_cache *cache, unsigned int caps)
 		} else {
 			/* Cache full, replace the last entry */
 			result = prev;
+			if (tail != NULL)
+				tail->next = NULL;
 			prev = NULL;
 
 			rb_linebuf_donebuf(&result->linebuf);