From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0BE0672 for ; Thu, 14 Oct 2021 00:44:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634172280; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=jFv5OLM8EkJT7hF4OqXauqHE4zCaE1+d14pWIYx+RA0=; b=bXhf/vco5QWw5NUYxvHUBDjBxj5Gtc4sA0g0IFKXpUX2X7cHIyPYIn9YdXEVVLozSYJCX5 xX9yfAstL23C56XU/SnUitySnv7oy5wOxxsgVLUkzsBLuVpww+dsO96uzyQnBHIHgVbuf2 RY3OXufB9gjzs2Zvz2dx5Ch7hS42wb4= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-574-v5w659QuP3K4udtIn8pCUQ-1; Wed, 13 Oct 2021 20:44:38 -0400 X-MC-Unique: v5w659QuP3K4udtIn8pCUQ-1 Received: by mail-qk1-f198.google.com with SMTP id v14-20020a05620a0f0e00b0043355ed67d1so3246668qkl.7 for ; Wed, 13 Oct 2021 17:44:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=jFv5OLM8EkJT7hF4OqXauqHE4zCaE1+d14pWIYx+RA0=; b=H4wr8o8V+AK3h1WlIM8b2G29YePRyMOlbHwdKLuyvcqfl15R/7VAJLcUfWcl0ISXc5 kzUASxWHc2A8/gSDxCy3O1UrRPG5glMyo21GCBSZhdVRwXrFD4C14EoidxFWrOW7NpVu TL1/klihbxncodQzkvX0SQ0ZnyzELTdHd/iPsVZ/asWNDsmIMr12BXR4wi4UYC4WpIBW 1TiY9ppzLCuZRkwVV130wA6qHgljORYvnZGts0x51sCOQx1K+iQ7peEtCrDIlLJE5jcT Wl0F5KAk25o6djUf4tp25qtRTUefxzZ8WMK993wjGMVxUN2TnW4+1vBD7JkU48vdP3+g 2/rw== X-Gm-Message-State: AOAM533fN/TsJJLWJhcDYMuUqjgdrr7bboUKD3dPnWRqDqngZQx+7G3q TSwza6RVvVK57QTiZGjcJYjbd19Lja4atx+Zn+0E9dHMfvB9l2YaNvx9Riy+MFu3pjSnxvp9NYQ GQUF5v9Q2PXF62g== X-Received: by 2002:a37:b742:: with SMTP id h63mr2191209qkf.204.1634172278101; Wed, 13 Oct 2021 17:44:38 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxN7hRCKU/SKDN5he5DTJoX8aHISMFYBLbyiwc6It64vOfVpkP2EJr4BFnCIqPmfMZ5NSu/ig== X-Received: by 2002:a37:b742:: with SMTP id h63mr2191187qkf.204.1634172277891; Wed, 13 Oct 2021 17:44:37 -0700 (PDT) Received: from treble ([2600:1700:6e32:6c00::15]) by smtp.gmail.com with ESMTPSA id z19sm701005qts.96.2021.10.13.17.44.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Oct 2021 17:44:37 -0700 (PDT) Date: Wed, 13 Oct 2021 17:44:34 -0700 From: Josh Poimboeuf To: Sami Tolvanen Cc: x86@kernel.org, Kees Cook , Peter Zijlstra , Nathan Chancellor , Nick Desaulniers , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v5 01/15] objtool: Add CONFIG_CFI_CLANG support Message-ID: <20211014004434.vjbpkd4ykn7upvsw@treble> References: <20211013181658.1020262-1-samitolvanen@google.com> <20211013181658.1020262-2-samitolvanen@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20211013181658.1020262-2-samitolvanen@google.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jpoimboe@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline On Wed, Oct 13, 2021 at 11:16:44AM -0700, Sami Tolvanen wrote: > The upcoming CONFIG_CFI_CLANG support uses -fsanitize=cfi, the > non-canonical version of which hijacks function entry by changing > function relocation references to point to an intermediary jump table. > > For example: > > Relocation section '.rela.discard.func_stack_frame_non_standard' at offset 0x37e018 contains 6 entries: > Offset Info Type Symbol's Value Symbol's Name + Addend > 0000000000000000 0002944700000002 R_X86_64_PC32 00000000000023f0 do_suspend_lowlevel + 0 > 0000000000000008 0003c11900000001 R_X86_64_64 0000000000000008 xen_cpuid$e69bc59f4fade3b6f2b579b3934137df.cfi_jt + 0 > 0000000000000010 0003980900000001 R_X86_64_64 0000000000000060 machine_real_restart.cfi_jt + 0 > 0000000000000018 0003962b00000001 R_X86_64_64 0000000000000e18 kretprobe_trampoline.cfi_jt + 0 > 0000000000000020 000028f300000001 R_X86_64_64 0000000000000000 .rodata + 12 > 0000000000000028 000349f400000001 R_X86_64_64 0000000000000018 __crash_kexec.cfi_jt + 0 > > 0000000000000060 : > 60: e9 00 00 00 00 jmpq 65 > 61: R_X86_64_PLT32 machine_real_restart-0x4 > 65: cc int3 > 66: cc int3 > 67: cc int3 > > This breaks objtool vmlinux validation in many ways, including static > call site detection and the STACK_FRAME_NON_STANDARD() macro. > > Fix it by converting those relocations' symbol references back to their > original non-jump-table versions. Note this doesn't change the actual > relocations in the object itself, it just changes objtool's view of > them. This change is based on Josh's initial patch: > > https://lore.kernel.org/r/d743f4b36e120c06506567a9f87a062ae03da47f.1611263462.git.jpoimboe@redhat.com/ > > Reported-by: Sedat Dilek > Suggested-by: Josh Poimboeuf > Signed-off-by: Sami Tolvanen > Reviewed-by: Nick Desaulniers > Tested-by: Nick Desaulniers > Tested-by: Sedat Dilek Acked-by: Josh Poimboeuf -- Josh