From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 010D33857413 for ; Wed, 27 Apr 2022 13:25:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 010D33857413 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-427-mb5aJSKaN42o8nBx8MDYUw-1; Wed, 27 Apr 2022 09:25:24 -0400 X-MC-Unique: mb5aJSKaN42o8nBx8MDYUw-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CFAD01C07380; Wed, 27 Apr 2022 13:25:23 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.193.187]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4E736463EF2; Wed, 27 Apr 2022 13:25:23 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella via Libc-alpha Subject: Re: [PATCH v2 2/4] Consolidate stdio-lock.h References: <20220426191523.833171-1-adhemerval.zanella@linaro.org> <20220426191523.833171-3-adhemerval.zanella@linaro.org> Date: Wed, 27 Apr 2022 15:25:21 +0200 In-Reply-To: <20220426191523.833171-3-adhemerval.zanella@linaro.org> (Adhemerval Zanella via Libc-alpha's message of "Tue, 26 Apr 2022 16:15:21 -0300") Message-ID: <87o80mhd4u.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-11.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Apr 2022 13:25:29 -0000 * Adhemerval Zanella via Libc-alpha: > diff --git a/sysdeps/generic/stdio-lock.h b/sysdeps/generic/stdio-lock.h > index 14cf458bdd..fd61f0b5b7 100644 > --- a/sysdeps/generic/stdio-lock.h > +++ b/sysdeps/generic/stdio-lock.h > @@ -45,20 +45,13 @@ __libc_lock_define_recursive (typedef, _IO_lock_t) > #define _IO_cleanup_region_end(_doit) \ > __libc_cleanup_region_end (_doit) > > -#if defined _LIBC && IS_IN (libc) > - > -# ifdef __EXCEPTIONS > -# define _IO_acquire_lock(_fp) \ > +#define _IO_acquire_lock(_fp) \ > do { \ > - FILE *_IO_acquire_lock_file \ > - __attribute__((cleanup (_IO_acquire_lock_fct))) \ > - = (_fp); \ > - _IO_flockfile (_IO_acquire_lock_file); > -# else > -# define _IO_acquire_lock(_fp) _IO_acquire_lock_needs_exceptions_enabled > -# endif > -# define _IO_release_lock(_fp) ; } while (0) > - > -#endif > + _IO_cleanup_region_start((void (*) (void *)) &_IO_funlockfile, _fp); \ > + _IO_flockfile (_fp); > +#define _IO_release_lock(_fp) \ > + _IO_funlockfile (_fp); \ > + _IO_cleanup_region_end (0); \ > + } while (0) > > #endif /* stdio-lock.h */ I think this change replaces unwind tables for -fexceptions builds. If GCC can't turn the indirect call to the unlock function into a direct call, this will result in a loss of hardening due to the additional indirect function call. This change may also lose C++ unwinding compatibility for some fopencookie use cases, I think. Thanks, Florian