Encode: revert commit that introduces security holes

This reverts a portion of commit
0f33e03c7e91f63bcd07b5ddfc00101715fa1fc0 which introduces some security
holes in checking for UTF-8 malformations.  In particular, it allows
overflow in non-strict mode, and overlongs in either mode.

See discussion at https://github.com/dankogai/p5-encode/issues/64

This reversion is to make sure that we don't release even a development
version with known security holes.  A final disposition is still to be
determined

1 files changed, 12 insertions, 38 deletions

diff --git a/cpan/Encode/Encode.xs b/cpan/Encode/Encode.xs
index 6b4fae9f64..222f39b2ea 100644
--- a/cpan/Encode/Encode.xs
+++ b/cpan/Encode/Encode.xs
@@ -318,39 +318,6 @@ strict_utf8(pTHX_ SV* sv)
     return SvTRUE(*svp);
 }
 
-/*
- * https://github.com/dankogai/p5-encode/pull/56#issuecomment-231959126
- */
-#ifndef UNICODE_IS_NONCHAR
-#define UNICODE_IS_NONCHAR(c) ((c >= 0xFDD0 && c <= 0xFDEF) || (c & 0xFFFE) == 0xFFFE)
-#endif
-
-static UV
-convert_utf8_multi_seq(U8* s, STRLEN len, bool strict)
-{
-    UV uv;
-
-    if (strict && len > 4)
-        return 0;
-
-    uv = NATIVE_TO_UTF(*s) & UTF_START_MASK(len);
-
-    len--;
-    s++;
-
-    while (len--) {
-        if (!UTF8_IS_CONTINUATION(*s))
-            return 0;
-        uv = UTF8_ACCUMULATE(uv, *s);
-        s++;
-    }
-
-    if (strict && (UNICODE_IS_SURROGATE(uv) || UNICODE_IS_NONCHAR(uv) || uv > PERL_UNICODE_MAX))
-        return 0;
-
-    return uv;
-}
-
 static U8*
 process_utf8(pTHX_ SV* dst, U8* s, U8* e, SV *check_sv,
              bool encode, bool strict, bool stop_at_partial)
@@ -399,12 +366,19 @@ process_utf8(pTHX_ SV* dst, U8* s, U8* e, SV *check_sv,
                 goto malformed_byte;
             }
 
-            ulen = skip;
-            uv = convert_utf8_multi_seq(s, skip, strict);
-            if (uv == 0) {
+            uv = utf8n_to_uvuni(s, e - s, &ulen,
+                                UTF8_CHECK_ONLY | (strict ? UTF8_ALLOW_STRICT :
+                                                            UTF8_ALLOW_NONSTRICT)
+                               );
+#if 1 /* perl-5.8.6 and older do not check UTF8_ALLOW_LONG */
+        if (strict && uv > PERL_UNICODE_MAX)
+        ulen = (STRLEN) -1;
+#endif
+            if (ulen == (STRLEN) -1) {
                 if (strict) {
-                    uv = convert_utf8_multi_seq(s, skip, 0);
-                    if (uv == 0)
+                    uv = utf8n_to_uvuni(s, e - s, &ulen,
+                                        UTF8_CHECK_ONLY | UTF8_ALLOW_NONSTRICT);
+                    if (ulen == (STRLEN) -1)
                         goto malformed_byte;
                     goto malformed;
                 }