Fix a double free / segfault with utf8 regexps 
Debian #454792
[rt.cpan.org #48156]
[rt.cpan.org #40641]
upstream change 29204

UTF8_ALLOW_DEFAULT definition in utf8.h picked from upstream change 27688

diff --git a/embed.fnc b/embed.fnc
index edfbc0e..26524c7 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -1168,6 +1168,7 @@ Es	|void	|reguni		|NN const struct RExC_state_t *state|UV uv|NN char *s|NN STRLE
 Es	|regnode*|regclass	|NN struct RExC_state_t *state
 ERs	|I32	|regcurly	|NN const char *
 Es	|regnode*|reg_node	|NN struct RExC_state_t *state|U8 op
+Es	|UV	|reg_recode	|const char value|NULLOK SV **encp
 Es	|regnode*|regpiece	|NN struct RExC_state_t *state|NN I32 *flagp
 Es	|void	|reginsert	|NN struct RExC_state_t *state|U8 op|NN regnode *opnd
 Es	|void	|regoptail	|NN struct RExC_state_t *state|NN regnode *p|NN regnode *val
diff --git a/embed.h b/embed.h
index 2b38fd5..372b04f 100644
--- a/embed.h
+++ b/embed.h
@@ -1234,6 +1234,7 @@
 #define regclass		S_regclass
 #define regcurly		S_regcurly
 #define reg_node		S_reg_node
+#define reg_recode		S_reg_recode
 #define regpiece		S_regpiece
 #define reginsert		S_reginsert
 #define regoptail		S_regoptail
@@ -3277,6 +3278,7 @@
 #define regclass(a)		S_regclass(aTHX_ a)
 #define regcurly(a)		S_regcurly(aTHX_ a)
 #define reg_node(a,b)		S_reg_node(aTHX_ a,b)
+#define reg_recode(a,b)		S_reg_recode(aTHX_ a,b)
 #define regpiece(a,b)		S_regpiece(aTHX_ a,b)
 #define reginsert(a,b,c)	S_reginsert(aTHX_ a,b,c)
 #define regoptail(a,b,c)	S_regoptail(aTHX_ a,b,c)
diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 9b3134c..7d95216 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -1900,6 +1900,15 @@ recognized by Perl or by a user-supplied handler.  See L<attributes>.
 (W printf) Perl does not understand the given format conversion.  See
 L<perlfunc/sprintf>.
 
+=item Invalid escape in the specified encoding in regex; marked by <-- HERE in m/%s/
+
+(W regexp) The numeric escape (for example C<\xHH>) of value < 256
+didn't correspond to a single character through the conversion
+from the encoding specified by the encoding pragma.
+The escape was replaced with REPLACEMENT CHARACTER (U+FFFD) instead.
+The <-- HERE shows in the regular expression about where the
+escape was discovered.
+
 =item Invalid [] range "%s" in regex; marked by <-- HERE in m/%s/
 
 (F) The range specified in a character class had a minimum character
diff --git a/proto.h b/proto.h
index 6d185dd..ef6c0cf 100644
--- a/proto.h
+++ b/proto.h
@@ -1748,6 +1748,7 @@ STATIC I32	S_regcurly(pTHX_ const char *)
 			__attribute__warn_unused_result__;
 
 STATIC regnode*	S_reg_node(pTHX_ struct RExC_state_t *state, U8 op);
+STATIC UV	S_reg_recode(pTHX_ const char value, SV **encp);
 STATIC regnode*	S_regpiece(pTHX_ struct RExC_state_t *state, I32 *flagp);
 STATIC void	S_reginsert(pTHX_ struct RExC_state_t *state, U8 op, regnode *opnd);
 STATIC void	S_regoptail(pTHX_ struct RExC_state_t *state, regnode *p, regnode *val);
diff --git a/regcomp.c b/regcomp.c
index 928cf39..98d48dd 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -2791,6 +2791,39 @@ S_regpiece(pTHX_ RExC_state_t *pRExC_state, I32 *flagp)
 }
 
 /*
+ * reg_recode
+ *
+ * It returns the code point in utf8 for the value in *encp.
+ *    value: a code value in the source encoding
+ *    encp:  a pointer to an Encode object
+ *
+ * If the result from Encode is not a single character,
+ * it returns U+FFFD (Replacement character) and sets *encp to NULL.
+ */
+STATIC UV
+S_reg_recode(pTHX_ const char value, SV **encp)
+{
+    STRLEN numlen = 1;
+    SV * const sv = sv_2mortal(newSVpvn(&value, numlen));
+    const char * const s = encp && *encp ? sv_recode_to_utf8(sv, *encp)
+					 : SvPVX(sv);
+    const STRLEN newlen = SvCUR(sv);
+    UV uv = UNICODE_REPLACEMENT;
+
+    if (newlen)
+	uv = SvUTF8(sv)
+	     ? utf8n_to_uvchr((U8*)s, newlen, &numlen, UTF8_ALLOW_DEFAULT)
+	     : *(U8*)s;
+
+    if (!newlen || numlen != newlen) {
+	uv = UNICODE_REPLACEMENT;
+	if (encp)
+	    *encp = NULL;
+    }
+    return uv;
+}
+
+/*
  - regatom - the lowest level
  *
  * Optimization:  gobbles an entire sequence of ordinary characters so that
@@ -3182,6 +3215,8 @@ tryagain:
 			    ender = grok_hex(p, &numlen, &flags, NULL);
 			    p += numlen;
 			}
+			if (PL_encoding && ender < 0x100)
+			    goto recode_encoding;
 			break;
 		    case 'c':
 			p++;
@@ -3201,6 +3236,17 @@ tryagain:
 			    --p;
 			    goto loopdone;
 			}
+			if (PL_encoding && ender < 0x100)
+			    goto recode_encoding;
+			break;
+		    recode_encoding:
+			{
+			    SV* enc = PL_encoding;
+			    ender = reg_recode((const char)(U8)ender, &enc);
+			    if (!enc && SIZE_ONLY && ckWARN(WARN_REGEXP))
+				vWARN(p, "Invalid escape in the specified encoding");
+			    RExC_utf8 = 1;
+			}
 			break;
 		    case '\0':
 			if (p >= RExC_end)
@@ -3331,32 +3377,6 @@ tryagain:
 	break;
     }
 
-    /* If the encoding pragma is in effect recode the text of
-     * any EXACT-kind nodes. */
-    if (PL_encoding && PL_regkind[(U8)OP(ret)] == EXACT) {
-	STRLEN oldlen = STR_LEN(ret);
-	SV *sv        = sv_2mortal(newSVpvn(STRING(ret), oldlen));
-
-	if (RExC_utf8)
-	    SvUTF8_on(sv);
-	if (sv_utf8_downgrade(sv, TRUE)) {
-	    const char * const s = sv_recode_to_utf8(sv, PL_encoding);
-	    const STRLEN newlen = SvCUR(sv);
-
-	    if (SvUTF8(sv))
-		RExC_utf8 = 1;
-	    if (!SIZE_ONLY) {
-		DEBUG_r(PerlIO_printf(Perl_debug_log, "recode %*s to %*s\n",
-				      (int)oldlen, STRING(ret),
-				      (int)newlen, s));
-		Copy(s, STRING(ret), newlen, char);
-		STR_LEN(ret) += newlen - oldlen;
-		RExC_emit += STR_SZ(newlen) - STR_SZ(oldlen);
-	    } else
-		RExC_size += STR_SZ(newlen) - STR_SZ(oldlen);
-	}
-    }
-
     return(ret);
 }
 
@@ -3734,6 +3754,8 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state)
 		    value = grok_hex(RExC_parse, &numlen, &flags, NULL);
 		    RExC_parse += numlen;
 		}
+		if (PL_encoding && value < 0x100)
+		    goto recode_encoding;
 		break;
 	    case 'c':
 		value = UCHARAT(RExC_parse++);
@@ -3741,13 +3763,24 @@ S_regclass(pTHX_ RExC_state_t *pRExC_state)
 		break;
 	    case '0': case '1': case '2': case '3': case '4':
 	    case '5': case '6': case '7': case '8': case '9':
-            {
-                I32 flags = 0;
-		numlen = 3;
-		value = grok_oct(--RExC_parse, &numlen, &flags, NULL);
-		RExC_parse += numlen;
-		break;
-            }
+		{
+		    I32 flags = 0;
+		    numlen = 3;
+		    value = grok_oct(--RExC_parse, &numlen, &flags, NULL);
+		    RExC_parse += numlen;
+		    if (PL_encoding && value < 0x100)
+			goto recode_encoding;
+		    break;
+		}
+	    recode_encoding:
+		{
+		    SV* enc = PL_encoding;
+		    value = reg_recode((const char)(U8)value, &enc);
+		    if (!enc && SIZE_ONLY && ckWARN(WARN_REGEXP))
+			vWARN(RExC_parse,
+			      "Invalid escape in the specified encoding");
+		    break;
+		}
 	    default:
 		if (!SIZE_ONLY && isALPHA(value) && ckWARN(WARN_REGEXP))
 		    vWARN2(RExC_parse,
diff --git a/t/uni/tr_utf8.t b/t/uni/tr_utf8.t
index 606a84a..354156a 100755
--- a/t/uni/tr_utf8.t
+++ b/t/uni/tr_utf8.t
@@ -31,7 +31,7 @@ BEGIN {
 }
 
 use strict;
-use Test::More tests => 7;
+use Test::More tests => 8;
 
 use encoding 'utf8';
 
@@ -67,4 +67,12 @@ is($str, $hiragana, "s/// # hiragana -> katakana");
   $line =~ tr/bcdeghijklmnprstvwxyz$02578/בצדעגהיײקלמנפּרסטװשכיזשױתײחא/;
   is($line, "aבצדעfגהיײקלמנoפqּרסuטװשכיזש1ױ34ת6ײח9", "[perl #16843]");
 }
+
+{
+  # [perl #40641]
+  my $str = qq/Gebääääääääääääääääääääude/;
+  my $reg = qr/Gebääääääääääääääääääääude/;
+  ok($str =~ /$reg/, "[perl #40641]");
+}
+
 __END__
diff --git a/utf8.h b/utf8.h
index 6d63897..3800866 100644
--- a/utf8.h
+++ b/utf8.h
@@ -198,6 +198,8 @@ encoded character.
 					 UTF8_ALLOW_SURROGATE|UTF8_ALLOW_FFFF)
 #define UTF8_ALLOW_ANY			0x00FF
 #define UTF8_CHECK_ONLY			0x0200
+#define UTF8_ALLOW_DEFAULT             (ckWARN(WARN_UTF8) ? 0 : \
+                                        UTF8_ALLOW_ANYUV)
 
 #define UNICODE_SURROGATE_FIRST		0xD800
 #define UNICODE_SURROGATE_LAST		0xDFFF