From owner-svn-src-stable@freebsd.org Wed May 2 08:27:00 2018 Return-Path: Delivered-To: svn-src-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8CD12FC5E8C; Wed, 2 May 2018 08:27:00 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 39FCD75723; Wed, 2 May 2018 08:27:00 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 2F1596882; Wed, 2 May 2018 08:27:00 +0000 (UTC) (envelope-from kib@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w428R0WT095371; Wed, 2 May 2018 08:27:00 GMT (envelope-from kib@FreeBSD.org) Received: (from kib@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w428R0Bg095370; Wed, 2 May 2018 08:27:00 GMT (envelope-from kib@FreeBSD.org) Message-Id: <201805020827.w428R0Bg095370@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: kib set sender to kib@FreeBSD.org using -f From: Konstantin Belousov Date: Wed, 2 May 2018 08:27:00 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r333168 - stable/11/lib/libc/secure X-SVN-Group: stable-11 X-SVN-Commit-Author: kib X-SVN-Commit-Paths: stable/11/lib/libc/secure X-SVN-Commit-Revision: 333168 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-stable@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for all the -stable branches of the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 02 May 2018 08:27:00 -0000 Author: kib Date: Wed May 2 08:26:59 2018 New Revision: 333168 URL: https://svnweb.freebsd.org/changeset/base/333168 Log: MFC r332940: Carefully update stack guard bytes inside __guard_setup(). Modified: stable/11/lib/libc/secure/stack_protector.c Directory Properties: stable/11/ (props changed) Modified: stable/11/lib/libc/secure/stack_protector.c ============================================================================== --- stable/11/lib/libc/secure/stack_protector.c Wed May 2 08:24:59 2018 (r333167) +++ stable/11/lib/libc/secure/stack_protector.c Wed May 2 08:26:59 2018 (r333168) @@ -54,15 +54,27 @@ static void __guard_setup(void) { static const int mib[2] = { CTL_KERN, KERN_ARND }; + volatile long tmp_stack_chk_guard[nitems(__stack_chk_guard)]; size_t len; - int error; + int error, idx; if (__stack_chk_guard[0] != 0) return; - error = _elf_aux_info(AT_CANARY, __stack_chk_guard, - sizeof(__stack_chk_guard)); - if (error == 0 && __stack_chk_guard[0] != 0) + /* + * Avoid using functions which might have stack protection + * enabled, to update the __stack_chk_guard. First fetch the + * data into a temporal array, then do manual volatile copy to + * not allow optimizer to call memcpy() behind us. + */ + error = _elf_aux_info(AT_CANARY, (void *)tmp_stack_chk_guard, + sizeof(tmp_stack_chk_guard)); + if (error == 0 && tmp_stack_chk_guard[0] != 0) { + for (idx = 0; idx < nitems(__stack_chk_guard); idx++) { + __stack_chk_guard[idx] = tmp_stack_chk_guard[idx]; + tmp_stack_chk_guard[idx] = 0; + } return; + } len = sizeof(__stack_chk_guard); if (__sysctl(mib, nitems(mib), __stack_chk_guard, &len, NULL, 0) ==