conncache: download buffer needs +1 size for trailing zero

Follow-up to c4e6968127e
Detected by OSS-Fuzz: https://oss-fuzz.com/testcase-detail/5727799779524608

diff --git a/lib/conncache.c b/lib/conncache.c
index f98e2297856267c3b50768a9930e012c1af88d19..d21a00cfdd9c208e9fd667bc1f57d4905e6a21ed 100644 (file)
--- a/lib/conncache.c
+++ b/lib/conncache.c
@@ -534,7 +534,7 @@ Curl_conncache_extract_oldest(struct Curl_easy *data)
 void Curl_conncache_close_all_connections(struct conncache *connc)
 {
   struct connectdata *conn;
-  char buffer[READBUFFER_MIN];
+  char buffer[READBUFFER_MIN + 1];
   if(!connc->closure_handle)
     return;
   connc->closure_handle->state.buffer = buffer;