12 files changed, 31 insertions, 14 deletions
diff --git a/src/lib/string/compat_ctype.c b/src/lib/string/compat_ctype.c
index f5d82be3ae..2357605021 100644
--- a/src/lib/string/compat_ctype.c
+++ b/src/lib/string/compat_ctype.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/compat_ctype.h b/src/lib/string/compat_ctype.h
index dbddd356c1..53ee6066f8 100644
--- a/src/lib/string/compat_ctype.h
+++ b/src/lib/string/compat_ctype.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/compat_string.c b/src/lib/string/compat_string.c
index 187f784be5..2bd3c2f2b4 100644
--- a/src/lib/string/compat_string.c
+++ b/src/lib/string/compat_string.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/compat_string.h b/src/lib/string/compat_string.h
index ffc892c3e5..f05265bdcc 100644
--- a/src/lib/string/compat_string.h
+++ b/src/lib/string/compat_string.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/parse_int.c b/src/lib/string/parse_int.c
index fd4422ecd0..11ce0fa415 100644
--- a/src/lib/string/parse_int.c
+++ b/src/lib/string/parse_int.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/parse_int.h b/src/lib/string/parse_int.h
index 50d48b44c5..27939ade61 100644
--- a/src/lib/string/parse_int.h
+++ b/src/lib/string/parse_int.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/printf.c b/src/lib/string/printf.c
index 26203932e4..86d860935e 100644
--- a/src/lib/string/printf.c
+++ b/src/lib/string/printf.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/printf.h b/src/lib/string/printf.h
index 6e90770f81..5ab751b338 100644
--- a/src/lib/string/printf.h
+++ b/src/lib/string/printf.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/scanf.c b/src/lib/string/scanf.c
index 1bc39b5182..89d1683204 100644
--- a/src/lib/string/scanf.c
+++ b/src/lib/string/scanf.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/scanf.h b/src/lib/string/scanf.h
index b642e242db..67e9c5eb78 100644
--- a/src/lib/string/scanf.h
+++ b/src/lib/string/scanf.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
diff --git a/src/lib/string/util_string.c b/src/lib/string/util_string.c
index f5061a11d2..c8f12d780e 100644
--- a/src/lib/string/util_string.c
+++ b/src/lib/string/util_string.c
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**
@@ -506,6 +506,23 @@ validate_char(const uint8_t *c, uint8_t len)
 int
 string_is_utf8(const char *str, size_t len)
 {
+  // If str is NULL, don't try to read it
+  if (!str) {
+    // We could test for this case, but the low-level logs would produce
+    // confusing test output.
+    // LCOV_EXCL_START
+    if (len) {
+      // Use the low-level logging function, so that the log module can
+      // validate UTF-8 (if needed in future code)
+      tor_log_err_sigsafe(
+        "BUG: string_is_utf8() called with NULL str but non-zero len.");
+      // Since it's a bug, we should probably reject this string
+      return false;
+    }
+    // LCOV_EXCL_STOP
+    return true;
+  }
+
   for (size_t i = 0; i < len;) {
     uint8_t num_bytes = bytes_in_char(str[i]);
     if (num_bytes == 0) // Invalid leading byte found.
@@ -530,8 +547,8 @@ string_is_utf8(const char *str, size_t len)
 int
 string_is_utf8_no_bom(const char *str, size_t len)
 {
-  if (len >= 3 && (!strcmpstart(str, "\uFEFF") ||
-                   !strcmpstart(str, "\uFFFE"))) {
+  if (str && len >= 3 && (!strcmpstart(str, "\uFEFF") ||
+                          !strcmpstart(str, "\uFFFE"))) {
     return false;
   }
   return string_is_utf8(str, len);
diff --git a/src/lib/string/util_string.h b/src/lib/string/util_string.h
index b3c6841d41..e89233df88 100644
--- a/src/lib/string/util_string.h
+++ b/src/lib/string/util_string.h
@@ -1,6 +1,6 @@
 /* Copyright (c) 2003-2004, Roger Dingledine
  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
- * Copyright (c) 2007-2019, The Tor Project, Inc. */
+ * Copyright (c) 2007-2020, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
 /**