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Fix #81243: Too much memory is allocated for preg_replace() #7231

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Fix #81243: Too much memory is allocated for preg_replace() #7231

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716274f
Fix #81243: Too much memory is allocated for preg_replace()
cmb69 Jul 12, 2021
c16fe09
Fix php_pcre_replace_func_impl(), too
cmb69 Jul 12, 2021
5b3564e
Allocate twice the size needed
cmb69 Jul 12, 2021
a417796
Fill out test name
cmb69 Jul 12, 2021
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32 changes: 14 additions & 18 deletions ext/pcre/php_pcre.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1719,7 +1719,7 @@ PHPAPI zend_string *php_pcre_replace_impl(pcre_cache_entry *pce, zend_string *su
}

if (new_len >= alloc_len) {
alloc_len = zend_safe_address_guarded(2, new_len, alloc_len);
alloc_len = zend_safe_address_guarded(2, new_len, 0);
if (result == NULL) {
result = zend_string_alloc(alloc_len, 0);
} else {
Expand Down Expand Up @@ -1805,14 +1805,12 @@ PHPAPI zend_string *php_pcre_replace_impl(pcre_cache_entry *pce, zend_string *su
result = zend_string_copy(subject_str);
break;
}
new_len = result_len + subject_len - last_end_offset;
if (new_len >= alloc_len) {
alloc_len = new_len; /* now we know exactly how long it is */
if (NULL != result) {
result = zend_string_realloc(result, alloc_len, 0);
} else {
result = zend_string_alloc(alloc_len, 0);
}
/* now we know exactly how long it is */
alloc_len = result_len + subject_len - last_end_offset;
if (NULL != result) {
result = zend_string_realloc(result, alloc_len, 0);
} else {
result = zend_string_alloc(alloc_len, 0);
}
/* stick that last bit of string on our output */
memcpy(ZSTR_VAL(result) + result_len, piece, subject_len - last_end_offset);
Expand Down Expand Up @@ -1959,7 +1957,7 @@ static zend_string *php_pcre_replace_func_impl(pcre_cache_entry *pce, zend_strin
ZEND_ASSERT(eval_result);
new_len = zend_safe_address_guarded(1, ZSTR_LEN(eval_result), new_len);
if (new_len >= alloc_len) {
alloc_len = zend_safe_address_guarded(2, new_len, alloc_len);
alloc_len = zend_safe_address_guarded(2, new_len, 0);
if (result == NULL) {
result = zend_string_alloc(alloc_len, 0);
} else {
Expand Down Expand Up @@ -2016,14 +2014,12 @@ static zend_string *php_pcre_replace_func_impl(pcre_cache_entry *pce, zend_strin
result = zend_string_copy(subject_str);
break;
}
new_len = result_len + subject_len - last_end_offset;
if (new_len >= alloc_len) {
alloc_len = new_len; /* now we know exactly how long it is */
if (NULL != result) {
result = zend_string_realloc(result, alloc_len, 0);
} else {
result = zend_string_alloc(alloc_len, 0);
}
/* now we know exactly how long it is */
alloc_len = result_len + subject_len - last_end_offset;
if (NULL != result) {
result = zend_string_realloc(result, alloc_len, 0);
} else {
result = zend_string_alloc(alloc_len, 0);
}
/* stick that last bit of string on our output */
memcpy(ZSTR_VAL(result) + result_len, piece, subject_len - last_end_offset);
Expand Down
21 changes: 21 additions & 0 deletions ext/pcre/tests/bug81243.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
--TEST--
Bug #81243 (Too much memory is allocated for preg_replace())
--FILE--
<?php
$test_string = str_repeat('Eins zwei drei', 2000);

$replaced = preg_replace('/\s/', '-', $test_string);
$mem0 = memory_get_usage();
$replaced = str_repeat($replaced, 1);
$mem1 = memory_get_usage();
var_dump($mem0 == $mem1);

$replaced = preg_replace_callback('/\s/', function ($_) {return '-';}, $test_string);
$mem0 = memory_get_usage();
$replaced = str_repeat($replaced, 1);
$mem1 = memory_get_usage();
var_dump($mem0 == $mem1);
?>
--EXPECT--
bool(true)
bool(true)