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ext/standard: Reject null bytes in parse_str() #21942

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Merged
TimWolla merged 1 commit into from
May 4, 2026
+19 −1
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ext/standard: Reject null bytes in parse_str() #21942

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2 changes: 2 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,8 @@ PHP NEWS
(Weilin Du)
. getenv() and putenv() now raises a ValueError when the first argument
contains null bytes. (Weilin Du)
. parse_str() now raises a ValueError when the $string argument contains
null bytes. (Weilin Du)
. proc_open() now raises a ValueError when the $cwd argument contains
null bytes. (Weilin Du)

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2 changes: 2 additions & 0 deletions UPGRADING
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Expand Up @@ -97,6 +97,8 @@ PHP 8.6 UPGRADE NOTES
argument value is passed.
. getenv() and putenv() now raises a ValueError when the first argument
contains null bytes.
. parse_str() now raises a ValueError when the $string argument contains
null bytes.
. linkinfo() now raises a ValueError when the $path argument is empty.
. pathinfo() now raises a ValueError when an invalid $flag
argument value is passed.
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2 changes: 1 addition & 1 deletion ext/standard/string.c
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Expand Up @@ -5012,7 +5012,7 @@ PHP_FUNCTION(parse_str)
size_t arglen;

ZEND_PARSE_PARAMETERS_START(2, 2)
Z_PARAM_STRING(arg, arglen)
Z_PARAM_PATH(arg, arglen)

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@LamentXU123 LamentXU123 May 4, 2026

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the implementation of parse_str is based on C str, and therefore if the parsed string contains NUL bytes it will truncates the trailing part. Now, we have already done the same fix of getenv and putenv. From this fix we can throw a ValueError to users instead of silently truncate the input.

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@mvorisek mvorisek May 4, 2026

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I see, it would be great to add a comment here, that the limitation is due php_default_treat_data not supporting an explicit input string length.

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@LamentXU123 LamentXU123 May 4, 2026

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Uh yes.That'd improve readability. Humm, we have lots of similar fix out there so adding comments to this case alone seems not to be effective... Could you please send a PR after this is merged to add this line of comment to every similar fix we have done before (i.e. reject NUL bytes because it silently truncates stuff)? Thank in advance!

Z_PARAM_ZVAL(arrayArg)
ZEND_PARSE_PARAMETERS_END();

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14 changes: 14 additions & 0 deletions ext/standard/tests/strings/parse_str_null_bytes.phpt
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@@ -0,0 +1,14 @@
--TEST--
parse_str() rejects null bytes
--FILE--
<?php

try {
parse_str("a=1\0&b=2", $result);
} catch (ValueError $e) {
echo $e->getMessage(), "\n";
}

?>
--EXPECT--
parse_str(): Argument #1 ($string) must not contain any null bytes
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