From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D87E7C56201 for ; Mon, 26 Oct 2020 12:29:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABF3622202 for ; Mon, 26 Oct 2020 12:29:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1775130AbgJZM3h (ORCPT ); Mon, 26 Oct 2020 08:29:37 -0400 Received: from mail-ot1-f67.google.com ([209.85.210.67]:46782 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1775119AbgJZM3g (ORCPT ); Mon, 26 Oct 2020 08:29:36 -0400 Received: by mail-ot1-f67.google.com with SMTP id j21so2690120ota.13; Mon, 26 Oct 2020 05:29:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=0trfHgi8OBfd5iB69j5LL8jeOJ1Nb/421IvjhePhaus=; b=P+zlDX8Hgk/S9xxcgd506ahxBtu8rxysyBTc4iPdrjvaUKbAIYNXAzklq2sAXHfcdT 4zOl+sJ2I4EsX+ysfwgaFtIp72UAzGYVSLOPvF+7rEaf7n2sNg49vN9xroPjX9W7ix/w WE4/Am7rq952ISK+5wgv41hBKbfGPpC12JbSi0QdtNGx3Z24DWvMShNR6iLwpMmIld/V Cl3vz8QU7l24bWJe5h+7EEnnfzMMNiE2I3HTK173CU7NJkOwH2R7GA/Cp9j8Ft8XvQ3O NS6eW1NQBUzx0XKvJy/3hq0kCaG9seTK3IeK/3Rzb0LxjhtrTxyU0xRs1LlbIkzZmDnW y5xg== X-Gm-Message-State: AOAM531eY9L/FwrZLkaV9J3oHAKbC/BsZQCvHwKqpupJ1LbS0AUInOks 1iPCyBSNeiZM0MrFucyCj7d0TsG3BsDmzzs2Luw= X-Google-Smtp-Source: ABdhPJyBweNoUQCltnRnsquxLRWEfPnJGEis2BPFL9CWHQhByaLq9YhLr+yqM3AxsL8UQGje3+jKX3bZuCidiISTg8s= X-Received: by 2002:a05:6830:210a:: with SMTP id i10mr13055312otc.145.1603715374142; Mon, 26 Oct 2020 05:29:34 -0700 (PDT) MIME-Version: 1.0 References: <20200821194310.3089815-1-keescook@chromium.org> <20200821194310.3089815-14-keescook@chromium.org> In-Reply-To: <20200821194310.3089815-14-keescook@chromium.org> From: Geert Uytterhoeven Date: Mon, 26 Oct 2020 13:29:22 +0100 Message-ID: Subject: Re: [PATCH v6 13/29] arm64/build: Assert for unwanted sections To: Kees Cook Cc: Ingo Molnar , Ard Biesheuvel , Catalin Marinas , Mark Rutland , Peter Collingbourne , James Morse , Borislav Petkov , Ingo Molnar , Russell King , Masahiro Yamada , Arvind Sankar , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , "the arch/x86 maintainers" , clang-built-linux , Linux-Arch , linux-efi , Linux ARM , Linux Kernel Mailing List , Linux-Renesas Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kees, On Fri, Aug 21, 2020 at 9:56 PM Kees Cook wrote: > In preparation for warning on orphan sections, discard > unwanted non-zero-sized generated sections, and enforce other > expected-to-be-zero-sized sections (since discarding them might hide > problems with them suddenly gaining unexpected entries). > > Suggested-by: Ard Biesheuvel > Signed-off-by: Kees Cook This is now commit be2881824ae9eb92 ("arm64/build: Assert for unwanted sections") in v5.10-rc1, and is causing the following error with renesas_defconfig[1]: aarch64-linux-gnu-ld: warning: orphan section `.eh_frame' from `kernel/bpf/core.o' being placed in section `.eh_frame' aarch64-linux-gnu-ld: Unexpected GOT/PLT entries detected! aarch64-linux-gnu-ld: Unexpected run-time procedure linkages detected! I cannot reproduce this with the standard arm64 defconfig. I bisected the error to the aforementioned commit, but understand this is not the real reason. If I revert this commit, I still get: aarch64-linux-gnu-ld: warning: orphan section `.got.plt' from `arch/arm64/kernel/head.o' being placed in section `.got.plt' aarch64-linux-gnu-ld: warning: orphan section `.plt' from `arch/arm64/kernel/head.o' being placed in section `.plt' aarch64-linux-gnu-ld: warning: orphan section `.data.rel.ro' from `arch/arm64/kernel/head.o' being placed in section `.data.rel.ro' aarch64-linux-gnu-ld: warning: orphan section `.eh_frame' from `kernel/bpf/core.o' being placed in section `.eh_frame' I.e. including the ".eh_frame" warning. I have tried bisecting that warning (i.e. with be2881824ae9eb92 reverted), but that leads me to commit b3e5d80d0c48c0cc ("arm64/build: Warn on orphan section placement"), which is another red herring. Note that even on plain be2881824ae9eb92, I get: aarch64-linux-gnu-ld: Unexpected GOT/PLT entries detected! aarch64-linux-gnu-ld: Unexpected run-time procedure linkages detected! The parent commit obviously doesn't show that (but probably still has the problem). Do you have a clue! Thanks! > --- a/arch/arm64/kernel/vmlinux.lds.S > +++ b/arch/arm64/kernel/vmlinux.lds.S > @@ -121,6 +121,14 @@ SECTIONS > *(.got) /* Global offset table */ > } > > + /* > + * Make sure that the .got.plt is either completely empty or it > + * contains only the lazy dispatch entries. > + */ > + .got.plt : { *(.got.plt) } > + ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, > + "Unexpected GOT/PLT entries detected!") > + > . = ALIGN(SEGMENT_ALIGN); > _etext = .; /* End of text section */ > > @@ -243,6 +251,18 @@ SECTIONS > ELF_DETAILS > > HEAD_SYMBOLS > + > + /* > + * Sections that should stay zero sized, which is safer to > + * explicitly check instead of blindly discarding. > + */ > + .plt : { > + *(.plt) *(.plt.*) *(.iplt) *(.igot) > + } > + ASSERT(SIZEOF(.plt) == 0, "Unexpected run-time procedure linkages detected!") > + > + .data.rel.ro : { *(.data.rel.ro) } > + ASSERT(SIZEOF(.data.rel.ro) == 0, "Unexpected RELRO detected!") > } > > #include "image-vars.h" [1] https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-devel.git/log/?h=topic/renesas-defconfig Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds