From 6efb877973fd66ad905d423bebe062bf7dd7c6ba Mon Sep 17 00:00:00 2001
From: Ting-Yuan Huang <laszio@google.com>
Date: Tue, 7 Feb 2017 16:40:35 -0800
Subject: [PATCH] liblog: fix an undefined-behavor in __write_to_log_daemon()

The behavior of passing NULL to c-string functions is undefined.

Test: passed clang-tidy checks
Bug: none

Change-Id: Ie7bcc43cd19bc4a1c314381af3929eae0a6154b9
---
 liblog/logger_write.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/liblog/logger_write.c b/liblog/logger_write.c
index 43241254f..2599a5394 100644
--- a/liblog/logger_write.c
+++ b/liblog/logger_write.c
@@ -343,7 +343,7 @@ static int __write_to_log_daemon(log_id_t log_id, struct iovec *vec, size_t nr)
             }
         }
         /* tag must be nul terminated */
-        if (strnlen(tag, len) >= len) {
+        if (tag && strnlen(tag, len) >= len) {
             tag = NULL;
         }