mb_str_pad causes access violation ( 0xc0000005) in mbstring.dll

[guyphp1]

Description

Running this single code line from command line:

$a = mb_str_pad("a", 10);

Resulted in this output:
Nom de l’application défaillante : php.exe, version : 8.3.0.0, horodatage : 0x649cc5d6
Nom du module défaillant : php_mbstring.dll, version : 8.3.0.0, horodatage : 0x649cc63c
Code d’exception : 0xc0000005
Décalage du défaut : 0x000000000000a489
ID processus défaillant : 0x0x1104
Heure de démarrage de l’application défaillante : 0x0x1D9AB58783DFCB0
Chemin de l’application défaillante : C:\atemp\php.exe
Chemin du module défaillant : C:\atemp\ext\php_mbstring.dll

PHP Version

PHP 8.3.0alpha3 64bit TS from github june 28

Operating System

Windows 11 64bits

[youkidearitai]

Reproduced it.

I tried fix to following code. What do you think @nielsdos ?:

diff --git a/ext/mbstring/mbstring.c b/ext/mbstring/mbstring.c
index 05c26c652c..42ba5761e0 100644
--- a/ext/mbstring/mbstring.c
+++ b/ext/mbstring/mbstring.c
@@ -5549,7 +5549,7 @@ PHP_FUNCTION(mb_str_pad)
                RETURN_STR_COPY(input);
        }

-       if (ZSTR_LEN(pad) == 0) {
+       if (pad == NULL || ZSTR_LEN(pad) == 0) {
                zend_argument_value_error(3, "must be a non-empty string");
                RETURN_THROWS();
        }

[nielsdos]

Thanks @youkidearitai . Unfortunately that's not quite right because pad is optional. I committed the fix for this issue, the commit message contains a short description of what happened and why the tests didn't catch this issue.

[youkidearitai]

@nielsdos Thank you very much! Confirmed to fix to this.