Fix #78454: Consecutive numeric separators cause OOM error

Resolves out of memory error when consecutive numeric separators follow a binary/hex literal.

Author: theodorejb

NEWS

@@ -9,6 +9,8 @@ PHP                                                                        NEWS
     (cmb, Nikita)
   . Fixed bug #78441 (Parse error due to heredoc identifier followed by digit).
     (cmb)
+  . Fixed bug #78454 (Consecutive numeric separators cause OOM error).
+    (Theodore Brown)
 
 - SPL:
   . Fixed bug #78436 (Missing addref in SplPriorityQueue EXTR_BOTH mode).

Zend/tests/bug78454_1.phpt

@@ -0,0 +1,7 @@
+--TEST--
+Invalid consecutive numeric separators after hex literal
+--FILE--
+<?php
+0x0__F;
+--EXPECTF--
+Parse error: syntax error, unexpected '__F' (T_STRING) in %s on line %d

Zend/tests/bug78454_2.phpt

@@ -0,0 +1,7 @@
+--TEST--
+Invalid consecutive numeric separators after binary literal
+--FILE--
+<?php
+0b0__1
+--EXPECTF--
+Parse error: syntax error, unexpected '__1' (T_STRING) in %s on line %d

Zend/zend_language_scanner.l

@@ -1775,7 +1775,7 @@ NEWLINE ("\r"|"\n"|"\r\n")
 	char *end, *bin = yytext + 2;
 
 	/* Skip any leading 0s */
-	while (*bin == '0' || *bin == '_') {
+	while (len > 0 && (*bin == '0' || *bin == '_')) {
 		++bin;
 		--len;
 	}
@@ -1892,7 +1892,7 @@ NEWLINE ("\r"|"\n"|"\r\n")
 	char *end, *hex = yytext + 2;
 
 	/* Skip any leading 0s */
-	while (*hex == '0' || *hex == '_') {
+	while (len > 0 && (*hex == '0' || *hex == '_')) {
 		++hex;
 		--len;
 	}