Re: com php-src: fix (signed) integer overflow (part of bug #52550: Zend/zend_hash.h

In that code path, it's possible that idx == LONG_MAX+1. Casting that value to a signed long is undefined behavior (since it overflows), which means that the compiler can do bad things with that. With this patch we will basically do the same operation, but over an unsigned long, thus avoiding the undefined behavior of signed integers. This patch prevents miscompilations by more aggressive compilers. Nuno -----Original Message----- Hi! Could you please explain this commit? idx is ulong, why this change improves anything?

Commit:    91ce8041a3e85594e81466a528f8d55cdc164c1f
Author:    Nuno Lopes <nlopess@php.net>         Mon, 2 Jul 2012 01:31:40 -0400

Parents: be4053cea0462c9de5396641f4e4fa2f56f5a675 Branches: PHP-5.4 Link: http://git.php.net/?p=php-src.git;a=commitdiff;h=91ce8041a3e85594e81466a528f8d55cdc164c1f Log: fix (signed) integer overflow (part of bug #52550 Bugs: https://bugs.php.net/52550 Changed paths: M Zend/zend_hash.h Diff: diff --git a/Zend/zend_hash.h b/Zend/zend_hash.h index 84ca1de..5c3b1cd 100644 --- a/Zend/zend_hash.h +++ b/Zend/zend_hash.h @@ -330,7 +330,7 @@ END_EXTERN_C() if (idx-1 > LONG_MAX) { /* overflow */ \ break; \ } \ - idx = (ulong)(-(long)idx); \

+ idx = -idx;               \

} else if (idx > LONG_MAX) { /* overflow */ \ break; \ } \