string.c: do not interpret '\\' before '\0' (CVE-2019-15846)

[exim.git] / src / src / utf8.c

diff --git a/src/src/utf8.c b/src/src/utf8.c
index be5bcb0788176a22bc884502fda86a9ad2a5a27d..16a53037de383165904c11bb33aee7d532e76253 100644 (file)
--- a/src/src/utf8.c
+++ b/src/src/utf8.c
@@ -2,7 +2,7 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) Jeremy Harris 2015, 2016 */
+/* Copyright (c) Jeremy Harris 2015 - 2018 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 
@@ -52,6 +52,10 @@ uschar * s1, * s;
 int rc;
 
 #ifdef SUPPORT_I18N_2008
+/* Avoid lowercasing plain-ascii domains */
+if (!string_is_utf8(utf8))
+  return string_copy(utf8);
+
 /* Only lowercase is accepted by the library call.  A pity since we lose
 any mixed-case annotation.  This does not really matter for a domain. */
   {
@@ -64,7 +68,7 @@ any mixed-case annotation.  This does not really matter for a domain. */
     break;
     }
   }
-if ((rc = idn2_lookup_u8(CCS s, &s1, IDN2_NFC_INPUT)) != IDN2_OK)
+if ((rc = idn2_lookup_u8((const uint8_t *) s, &s1, IDN2_NFC_INPUT)) != IDN2_OK)
   {
   if (err) *err = US idn2_strerror(rc);
   return NULL;
@@ -93,7 +97,7 @@ string_domain_alabel_to_utf8(const uschar * alabel, uschar ** err)
 #ifdef SUPPORT_I18N_2008
 const uschar * label;
 int sep = '.';
-uschar * s = NULL;
+gstring * g = NULL;
 
 while (label = string_nextinlist(&alabel, &sep, NULL, 0))
   if (  string_is_alabel(label)
@@ -101,8 +105,8 @@ while (label = string_nextinlist(&alabel, &sep, NULL, 0))
      )
     return NULL;
   else
-    s = string_append_listele(s, '.', label);
-return s;
+    g = string_append_listele(g, '.', label);
+return string_from_gstring(g);
 
 #else
 
@@ -198,7 +202,7 @@ return NULL;
 /* Whole address conversion.
 The *err string pointer should be null before the call.
 
-Return NULL on oeeror, with (optional) errstring pointer filled in
+Return NULL on error, with (optional) errstring pointer filled in
 */
 
 uschar *