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GH-24203 follow-up: Stricter bcrypt hash format validation #24302

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GH-24203 follow-up: Stricter bcrypt hash format validation #24302

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2ae6b1a
GH-24203 follow-up: Stricter bcrypt hash format validation
narfbg Oct 13, 2026
e12ea56
GH-24302 php_password_bcrypt_parse() guard against sscanf() quirks
narfbg Oct 15, 2026
18dd432
GH-24302 Revert away from sscanf() usage
narfbg Nov 3, 2026
bd93ce7
Make bcrypt_get_cost() assign a default
narfbg Nov 4, 2026
dcde500
Remove redundant cost initialization
narfbg Nov 4, 2026
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64 changes: 40 additions & 24 deletions ext/standard/password.c
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Original file line number Diff line number Diff line change
Expand Up @@ -113,30 +113,54 @@ static zend_string* php_password_get_salt(zval *unused_, size_t required_salt_le

/* bcrypt implementation */

static bool php_password_bcrypt_get_cost(const zend_string *hash, zend_long *cost) {
static bool php_password_bcrypt_get_cost(zend_array *options, zend_long *cost) {
zval *zcost;
if (options && (zcost = zend_hash_str_find(options, "cost", sizeof("cost")-1)) != NULL) {
*cost = zval_get_long(zcost);
return *cost >= 4 && *cost <= 31;
}

*cost = PHP_PASSWORD_BCRYPT_COST;
return true;
}

static bool php_password_bcrypt_parse(const zend_string *hash, zend_long *cost) {
const char *h = ZSTR_VAL(hash);

if ((ZSTR_LEN(hash) != 60) ||
(h[0] != '$') || (h[1] != '2') || (h[2] != 'y') || (h[3] != '$') ||
!ZEND_IS_DIGIT(h[4]) || !ZEND_IS_DIGIT(h[5]) || (h[6] != '$')) {
if (ZSTR_LEN(hash) != 60 ||
h[0] != '$' || h[1] != '2' || h[2] != 'y' || h[3] != '$' ||
!ZEND_IS_DIGIT(h[4]) || !ZEND_IS_DIGIT(h[5]) || h[6] != '$' ||
(h[28] != '.' && h[28] != 'O' && h[28] != 'e' && h[28] != 'u')
) {
return false;
}

*cost = (h[4] - '0') * 10 + (h[5] - '0');
unsigned char c = (h[4] - '0') * 10 + (h[5] - '0');
if (c < 4 || c > 31) {
return false;
}

for (size_t i = 7; i < 60; i++) {
if (h[i] < '.' || h[i] > 'z' || (h[i] > '9' && h[i] < 'A') || (h[i] > 'Z' && h[i] < 'a')) {
return false;
}
}

if (cost != NULL) {
*cost = (zend_long) c;
}

return *cost >= 4 && *cost <= 31;
return true;
}

static bool php_password_bcrypt_valid(const zend_string *hash) {
zend_long cost;

return php_password_bcrypt_get_cost(hash, &cost);
return php_password_bcrypt_parse(hash, NULL);
}

static int php_password_bcrypt_get_info(zval *return_value, const zend_string *hash) {
zend_long cost;

if (!php_password_bcrypt_get_cost(hash, &cost)) {
if (!php_password_bcrypt_parse(hash, &cost)) {
/* Should never get called this way. */
return FAILURE;
}
Expand All @@ -146,17 +170,14 @@ static int php_password_bcrypt_get_info(zval *return_value, const zend_string *h
}

static bool php_password_bcrypt_needs_rehash(const zend_string *hash, zend_array *options) {
zval *znew_cost;
zend_long old_cost;
zend_long new_cost = PHP_PASSWORD_BCRYPT_COST;
zend_long old_cost, new_cost;

if (!php_password_bcrypt_get_cost(hash, &old_cost)) {
if (!php_password_bcrypt_parse(hash, &old_cost)) {
/* Should never get called this way. */
return 1;
}
if (options && (znew_cost = zend_hash_str_find(options, "cost", sizeof("cost")-1)) != NULL) {
new_cost = zval_get_long(znew_cost);
}

php_password_bcrypt_get_cost(options, &new_cost);

return old_cost != new_cost;
}
Expand Down Expand Up @@ -188,19 +209,14 @@ static zend_string* php_password_bcrypt_hash(const zend_string *password, zend_a
char hash_format[10];
size_t hash_format_len;
zend_string *result, *hash, *salt;
zval *zcost;
zend_long cost = PHP_PASSWORD_BCRYPT_COST;
zend_long cost;

if (memchr(ZSTR_VAL(password), '\0', ZSTR_LEN(password))) {
zend_value_error("Bcrypt password must not contain null character");
return NULL;
}

if (options && (zcost = zend_hash_str_find(options, "cost", sizeof("cost")-1)) != NULL) {
cost = zval_get_long(zcost);
}

if (cost < 4 || cost > 31) {
if (!php_password_bcrypt_get_cost(options, &cost)) {
zend_value_error("Invalid bcrypt cost parameter specified: " ZEND_LONG_FMT, cost);
return NULL;
}
Expand Down
25 changes: 25 additions & 0 deletions ext/standard/tests/password/password_get_info.phpt
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ var_dump(password_get_info('$2y$10$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vj
var_dump(password_get_info('$2y$11$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100y'));
// Test Bcrypt Invalid Length
var_dump(password_get_info('$2y$11$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj100'));
var_dump(password_get_info('$2y$11$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR.oP7XOR9HD/vjUuOj1000y'));
// Test Non-Bcrypt
var_dump(password_get_info('$1$rasmusle$rISCgZzpwk3UhDidwXvin0'));

Expand All @@ -26,7 +27,15 @@ $invalidHashes = [
'below range' => '$2y$03$' . $suffix,
'above range' => '$2y$32$' . $suffix,
'missing separator' => '$2y$' . str_repeat('9', 56),
'malformed salt segment' => '$2y$04$MTIzNDU2Nzg5MDEyMzQ1NEj0NmcAWSLR.oP7XOR9HD/vjUuOj100y',
'malformed hash segment' => '$2y$04$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR+oP7XOR9HD/vjUuOj100y',
'malicious misalignment' => '$2y$4$MTIzNDU2Nzg5MDEyMzQ1Neej0NmcAWSLR+oP7XOR9HD/vjUuOj100y',
'minus sign' => '$2y$-4$' . $suffix,
'plus sign' => '$2y$+4$' . $suffix,
'newline' => '$2y$'."\n".'4$' . $suffix,
'space' => '$2y$ 4$' . $suffix,
];

foreach ($invalidHashes as $description => $hash) {
$info = password_get_info($hash);
printf("%s: %s, options %d\n", $description, $info['algoName'], count($info['options']));
Expand Down Expand Up @@ -75,11 +84,27 @@ array(3) {
array(0) {
}
}
array(3) {
["algo"]=>
NULL
["algoName"]=>
string(7) "unknown"
["options"]=>
array(0) {
}
}
valid 4: bcrypt, cost 4
valid 31: bcrypt, cost 31
non-digit: unknown, options 0
malformed separator: unknown, options 0
below range: unknown, options 0
above range: unknown, options 0
missing separator: unknown, options 0
malformed salt segment: unknown, options 0
malformed hash segment: unknown, options 0
malicious misalignment: unknown, options 0
minus sign: unknown, options 0
plus sign: unknown, options 0
newline: unknown, options 0
space: unknown, options 0
OK!
14 changes: 14 additions & 0 deletions ext/standard/tests/password/password_needs_rehash.phpt
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,10 @@ var_dump(password_needs_rehash('', PASSWORD_BCRYPT));
var_dump(password_needs_rehash('', 1));
var_dump(password_needs_rehash('', '2y'));

// Plausible-looking, but malformed hashes
var_dump(password_needs_rehash('$2y$04$MTIzNDU2Nzg5MDEyMzQ1NEj0NmcAWSLR.oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT));
var_dump(password_needs_rehash('$2y$04$MTIzNDU2Nzg5MDEyMzQ1Nej0NmcAWSLR+oP7XOR9HD/vjUuOj100y', PASSWORD_BCRYPT));

// Valid, as it's an unknown algorithm
var_dump(password_needs_rehash('', PASSWORD_DEFAULT));
var_dump(password_needs_rehash('', 0));
Expand Down Expand Up @@ -42,6 +46,10 @@ $costCases = [
'malformed separator' => ['$2y$10x' . $suffix, 10],
'below range' => ['$2y$03$' . $suffix, 3],
'above range' => ['$2y$32$' . $suffix, 32],
'minus sign' => ['$2y$-4$' . $suffix, 4],
'plus sign' => ['$2y$+4$' . $suffix, 4],
'newline' => ['$2y$'."\n".'4$' . $suffix, 4],
'space' => ['$2y$ 4$' . $suffix, 4],
];
foreach ($costCases as $description => $case) {
echo $description, ': ';
Expand All @@ -63,6 +71,8 @@ bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)
bool(false)
bool(false)
bool(true)
Expand All @@ -75,6 +85,10 @@ non-digit: bool(true)
malformed separator: bool(true)
below range: bool(true)
above range: bool(true)
minus sign: bool(true)
plus sign: bool(true)
newline: bool(true)
space: bool(true)
bool(true)
bool(true)
OK!
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