From 1f72417ee65a6072e44318bf545a3a4ed21ac7f8 Mon Sep 17 00:00:00 2001
From: Hongze Cheng <hzcheng@taosdata.com>
Date: Wed, 8 Jul 2020 21:33:10 +0800
Subject: [PATCH] fix invalid read

---
 src/util/src/tskiplist.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/util/src/tskiplist.c b/src/util/src/tskiplist.c
index f3c0babe6b..045de3aa2f 100644
--- a/src/util/src/tskiplist.c
+++ b/src/util/src/tskiplist.c
@@ -498,7 +498,17 @@ void tSkipListRemoveNode(SSkipList *pSkipList, SSkipListNode *pNode) {
   if (pSkipList->lock) {
     pthread_rwlock_wrlock(pSkipList->lock);
   }
-  
+
+  if (pSkipList->size == 1) {
+    assert(pSkipList->lastKey == SL_GET_NODE_KEY(pSkipList, pNode));
+    pSkipList->lastKey = 0;
+  } else {
+    if (pSkipList->lastKey == SL_GET_NODE_KEY(pSkipList, pNode)) {
+      SSkipListNode* prev = SL_GET_BACKWARD_POINTER(pNode, 0);
+      pSkipList->lastKey = SL_GET_NODE_KEY(pSkipList, prev);
+    }
+  }
+
   for (int32_t j = level - 1; j >= 0; --j) {
     SSkipListNode* prev = SL_GET_BACKWARD_POINTER(pNode, j);
     SSkipListNode* next = SL_GET_FORWARD_POINTER(pNode, j);
-- 
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