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Fix bounds check in multibyte UTF detection #23527

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Fix bounds check in multibyte UTF detection #23527

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20 changes: 20 additions & 0 deletions Zend/tests/multibyte/multibyte_encoding_008.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
--TEST--
Zend Multibyte does not read past the script during UTF-16 detection
--EXTENSIONS--
mbstring
--INI--
zend.multibyte=1
internal_encoding=UTF-8
--FILE--
<?php
$filename = __DIR__ . '/multibyte_encoding_008.tmp.php';
file_put_contents($filename, "<\0?\0p\0h\0p\0");
include $filename;
echo "Done\n";
?>
--CLEAN--
<?php
@unlink(__DIR__ . '/multibyte_encoding_008.tmp.php');
?>
--EXPECT--
Done
17 changes: 8 additions & 9 deletions Zend/zend_language_scanner.l
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Original file line number Diff line number Diff line change
Expand Up @@ -327,14 +327,13 @@ ZEND_API zend_result zend_lex_tstring(zval *zv, unsigned char *ident)
static const zend_encoding *zend_multibyte_detect_utf_encoding(const unsigned char *script, size_t script_size)
{
const unsigned char *p;
size_t offset = 0;
int wchar_size = 2;
int le = 0;

/* utf-16 or utf-32? */
p = script;
assert(p >= script);
while ((size_t)(p-script) < script_size) {
p = memchr(p, 0, script_size-(p-script)-2);
while (offset < script_size && script_size - offset > 2) {
p = memchr(script + offset, 0, script_size - offset - 2);
if (!p) {
break;
}
Expand All @@ -344,13 +343,13 @@ static const zend_encoding *zend_multibyte_detect_utf_encoding(const unsigned ch
}

/* searching for UTF-32 specific byte orders, so this will do */
p += 4;
offset = p - script + 4;
}

/* BE or LE? */
p = script;
assert(p >= script);
while ((size_t)(p-script) < script_size) {
offset = 0;
while (script_size - offset >= (size_t) wchar_size) {
p = script + offset;
if (*p == '\0' && *(p+wchar_size-1) != '\0') {
/* BE */
le = 0;
Expand All @@ -360,7 +359,7 @@ static const zend_encoding *zend_multibyte_detect_utf_encoding(const unsigned ch
le = 1;
break;
}
p += wchar_size;
offset += wchar_size;
}

if (wchar_size == 2) {
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