From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.2 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by inbox.vuxu.org (OpenSMTPD) with SMTP id 04ded823 for ; Sun, 19 Jan 2020 11:31:48 +0000 (UTC) Received: (qmail 1288 invoked by uid 550); 19 Jan 2020 11:31:46 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 1265 invoked from network); 19 Jan 2020 11:31:46 -0000 Date: Sun, 19 Jan 2020 12:31:34 +0100 From: Szabolcs Nagy To: musl@lists.openwall.com Message-ID: <20200119113134.GJ23985@port70.net> Mail-Followup-To: musl@lists.openwall.com References: <20200119110743.GD2020@voyager> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200119110743.GD2020@voyager> User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [musl] Minor style patch to exit.c * Markus Wichmann [2020-01-19 12:07:43 +0100]: > The previous version did have a maze of parentheses here. But the actual > logic of the function is not to iterate over some numbers that happen to > be convertible to pointers, but rather to iterate over an array of > function pointers. So let us use pointer arithmetic correctly. > --- > src/exit/exit.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/src/exit/exit.c b/src/exit/exit.c > index a6869b37..e02ba2be 100644 > --- a/src/exit/exit.c > +++ b/src/exit/exit.c > @@ -16,9 +16,9 @@ extern weak hidden void (*const __fini_array_start)(void), (*const __fini_array_ > > static void libc_exit_fini(void) > { > - uintptr_t a = (uintptr_t)&__fini_array_end; > - for (; a>(uintptr_t)&__fini_array_start; a-=sizeof(void(*)())) > - (*(void (**)())(a-sizeof(void(*)())))(); > + void (*const *a)() = &__fini_array_end; > + while (a > &__fini_array_start) > + (*--a)(); this has undefined behaviour. the original code was carefully written to avoid that. you need to keep the uintptr_t cast since -- and > are undefined for pointers that go out of bound or don't point to the same object (and the _start, _end symbols don't represent the same c language object, they are independent). > _fini(); > } > > -- > 2.17.1 >