avoid off-by-one when at the maximum tag length

diff --git a/src/libserver/protocol.c b/src/libserver/protocol.c
index ccf26977d343a100874de4bd4cb1f434d7096825..83bcb6e2a8767aba6f2c302e2169ff64d4e760d5 100644 (file)
--- a/src/libserver/protocol.c
+++ b/src/libserver/protocol.c
@@ -713,7 +713,7 @@ rspamd_protocol_handle_headers(struct rspamd_task *task,
                                msg_debug_protocol("read log-tag header, value: %T", hv_tok);
                                /* Ensure that a tag is valid */
                                if (rspamd_fast_utf8_validate(hv_tok->begin, hv_tok->len) == 0) {
-                                       int len = MIN(hv_tok->len, sizeof(task->task_pool->tag.uid));
+                                       int len = MIN(hv_tok->len, sizeof(task->task_pool->tag.uid) - 1);
                                        memcpy(task->task_pool->tag.uid, hv_tok->begin, len);
                                        task->task_pool->tag.uid[len] = '\0';
                                }