From: Nikita Popov <nikita.ppv@gmail.com>
Date: Thu, 20 Jun 2019 12:52:12 +0000 (+0200)
Subject: FFI: Use signed arithmetic for pointer offset
X-Git-Tag: php-7.4.0alpha2~32
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f127d77eefad4b641b2befcbab13f16a624e7424;p=php

FFI: Use signed arithmetic for pointer offset

offset can be negative here, using signed arithmetic avoids ubsan
warnings.
---

diff --git a/ext/ffi/ffi.c b/ext/ffi/ffi.c
index 1b016c00a6..20a215a42a 100644
--- a/ext/ffi/ffi.c
+++ b/ext/ffi/ffi.c
@@ -1638,7 +1638,7 @@ static zend_object* zend_ffi_add(zend_ffi_cdata *base_cdata, zend_ffi_type *base
 	}
 	cdata->ptr = &cdata->ptr_holder;
 	cdata->ptr_holder = ptr +
-		offset * ZEND_FFI_TYPE(ptr_type)->size;
+		(ptrdiff_t) (offset * ZEND_FFI_TYPE(ptr_type)->size);
 	cdata->flags = base_cdata->flags & ZEND_FFI_FLAG_CONST;
 	return &cdata->std;
 }