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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,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 C9C8CCA9EC9 for ; Fri, 1 Nov 2019 04:00:51 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 1D063208E3 for ; Fri, 1 Nov 2019 04:00:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="gAic49MA" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1D063208E3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17222-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 5267 invoked by uid 550); 1 Nov 2019 04:00:45 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 5247 invoked from network); 1 Nov 2019 04:00:44 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=DqG2K0fvYUAA4E302d2Wr4MEutud0mjKuHdZBEE6NhQ=; b=gAic49MAeOc0RHQwT7q95mZfaWy/E6IhEpBpV5hJ3STSid/jPRu+sGJtzjSfKCXuEf cHqE/dxdIBbercFZyX9sSIjRyybd8IPXMMKNRCD5XgWMmq1WJvMLtGj8wgTBt16jV32H m8Pv3sMDvWULeXDkmLgUa3AZ6LDQXwbzmCxlc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=DqG2K0fvYUAA4E302d2Wr4MEutud0mjKuHdZBEE6NhQ=; b=s5qaVo7EmJ6RhC23Bx1SGL0yAD+zSVBBkNluJ0PiddwCdVB01ZAbbAw2RhAHbPgIG8 QAExSvBQKq/1RDhnaLGEQTYQDpjfRFoN6tO8l079u06MuFvfVPgSerURPX346L2I7Q2L gvOIVpsI3fGBt4A0nkunhkc2QHRZPG/haaGhyCwEsn6CoX2gRhbRtFFP2ZjchWOMcjrv nWUP0W9FlCu63eoDiSAPa2R8ZmDgh2KMo9AfoUVsPEfPDiia+FC2qeUUnshUK0QNCAYn UdRZkWXcgOYCvRKAQGMAzbIwn+RknwuPXRUcA9ZxT9DakUVEMF/v+BKd2vyc1CbaS7YY OMPg== X-Gm-Message-State: APjAAAVoTjk/X6IUUsLbrxn3HCRJSDB2W6hxF0zU0DH673xtHSe8FV2o hRUxOTB56jok1EXIGgISVfe+Pw== X-Google-Smtp-Source: APXvYqwjxz9PkVBJaSe/Y1M2wUY5vJE9zTstT50unKznJW5kGeoF7F85nWGFPaym5lZ0YmXY+dykwQ== X-Received: by 2002:aa7:90da:: with SMTP id k26mr1506175pfk.162.1572580833083; Thu, 31 Oct 2019 21:00:33 -0700 (PDT) Date: Thu, 31 Oct 2019 21:00:31 -0700 From: Kees Cook To: samitolvanen@google.com Cc: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Dave Martin , Laura Abbott , Mark Rutland , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 14/17] arm64: efi: restore x18 if it was corrupted Message-ID: <201910312100.E35C214206@keescook> References: <20191018161033.261971-1-samitolvanen@google.com> <20191031164637.48901-1-samitolvanen@google.com> <20191031164637.48901-15-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191031164637.48901-15-samitolvanen@google.com> On Thu, Oct 31, 2019 at 09:46:34AM -0700, samitolvanen@google.com wrote: > If we detect a corrupted x18 and SCS is enabled, restore the register > before jumping back to instrumented code. This is safe, because the > wrapper is called with preemption disabled and a separate shadow stack > is used for interrupt handling. > > Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook -Kees > --- > arch/arm64/kernel/efi-rt-wrapper.S | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S > index 3fc71106cb2b..945744f16086 100644 > --- a/arch/arm64/kernel/efi-rt-wrapper.S > +++ b/arch/arm64/kernel/efi-rt-wrapper.S > @@ -34,5 +34,10 @@ ENTRY(__efi_rt_asm_wrapper) > ldp x29, x30, [sp], #32 > b.ne 0f > ret > -0: b efi_handle_corrupted_x18 // tail call > +0: > +#ifdef CONFIG_SHADOW_CALL_STACK > + /* Restore x18 before returning to instrumented code. */ > + mov x18, x2 > +#endif > + b efi_handle_corrupted_x18 // tail call > ENDPROC(__efi_rt_asm_wrapper) > -- > 2.24.0.rc0.303.g954a862665-goog > -- Kees Cook