Merge pull request #8071 from azat/Connection-sendCancel-SIGSEGV

Avoid null dereference after "Unknown packet X from server" (cherry picked from commit bef3a0d)
ClickHouse · Dec 17, 2019 · fbb51a5 · fbb51a5
1 parent 2767862
commit fbb51a5
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/dbms/src/Client/Connection.cpp b/dbms/src/Client/Connection.cpp
@@ -434,6 +434,10 @@ void Connection::sendQuery(
 
 void Connection::sendCancel()
 {
+    /// If we already disconnected.
+    if (!out)
+        return;
+
     //LOG_TRACE(log_wrapper.get(), "Sending cancel");
 
     writeVarUInt(Protocol::Client::Cancel, *out);