From nobody Fri Oct 31 04:51:07 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D92CE80A8A for ; Wed, 27 Sep 2023 22:48:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229987AbjI0Wsd (ORCPT ); Wed, 27 Sep 2023 18:48:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230036AbjI0WsO (ORCPT ); Wed, 27 Sep 2023 18:48:14 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9342102 for ; Wed, 27 Sep 2023 15:48:12 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id d9443c01a7336-1c5fddcf2f1so135790325ad.0 for ; Wed, 27 Sep 2023 15:48:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695854892; x=1696459692; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=6h9NlhRD8hF3JGpC0yj7VRjIJqQSgsUALXY/NiPb6h0=; b=W9P9xxx/gnYx5osYpeI76vzlOzUEZfBvOLYTAO10FfRylT1mRq2bCMYcS1+hZft3AY eGZxePpApMxNN6c3WlWJBYdNELeMLib6wf1nyJ5oA4p5JDg7FCt1iW+URV2HCAkBPm2b eqQeNetpEjf0hkEkQ0YyuyF1TCs6Vs9UTvLLXUReoJtc6/JIdz05h1AAlp1beXi2B0lQ isFXBAT7jFPTgJQ8P+kuxLj6ro5eRYIb2ZFthvt5nDPRxsDGJoktPaerzsb8uVoQZzDu n62biOqvhU0Oo26flZg4+asLR8fOy1TKIRJYK5XRG5g8V4oNQYf9ODdXlY15hK8yzQ+i 2DEA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695854892; x=1696459692; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=6h9NlhRD8hF3JGpC0yj7VRjIJqQSgsUALXY/NiPb6h0=; b=oWKkRB7qu8zr+7JcouQvxbeuXqo44qFvVnYE5l3LGh3qHItGKZQPzuHtLfPKib4Z7r i+kAY4TGNeQMY+tgrEDYR9HZNP9mdfVKgLbFueL4HQbHEv/fHwsJFcFYtQbtckJOBNfd t5f2OWadFWaqvUy5qPluC6F9CjAg0/vAZKnpihor4NgXSTkldVJpqwlTJzcNnU1JWKFL mW3wrkTwHCR8SN8e6bz+aENjPI70aWUTEA4Sk78LXMrQ1tBUUyU3PfF2VCRLA44rSq6x N2emBL1gUzbYKm5yiPMIvr+cwFRTveCG2n7HNEpwIpjE3v1C526rh7wFAecR0X9aSY65 fFmw== X-Gm-Message-State: AOJu0Yz71/nrM7dM5v3awK3SlMAcAJPP+laIxxttpcyL8rpIQfq6OPIJ zQPVVIQ1P2mW0+EDwZ96/DBtniKs+XD9RA3ZdHE= X-Google-Smtp-Source: AGHT+IHK+0biBPVWxcHovzaXWOtINj3uMRtfg9f7R8EmqXuweOi238eHtIUJiD/eg0+vD4plv8qwETomHuFNs3pZDjQ= X-Received: from samitolvanen.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:4f92]) (user=samitolvanen job=sendgmr) by 2002:a17:903:2350:b0:1c6:d25:8750 with SMTP id c16-20020a170903235000b001c60d258750mr47383plh.10.1695854892186; Wed, 27 Sep 2023 15:48:12 -0700 (PDT) Date: Wed, 27 Sep 2023 22:48:04 +0000 In-Reply-To: <20230927224757.1154247-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20230927224757.1154247-8-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=2082; i=samitolvanen@google.com; h=from:subject; bh=4N5TA1RYsqEG6l9M0xplln+cBa1Qt0iz0MCbO5csiTU=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBlFLEdbuqhUGRkvHlpnRFoLVngxWUbGDzCKHZjB gXmrezGpZuJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCZRSxHQAKCRBMtfaEi7xW 7uL3C/9V/COsf71wMsf8LAD8PbXFSUssu/Ulme80Bc+IvZbku+VH0yCAi+0as+ACJEpRsTnNbIQ pScn4vacTqNH+5w4IriZtrxed/+JlJlJ3oFsv2kgI5IxJP44McljBfgT1GRyGCHurDabqPsJYX5 TaGUz9a7+gFF6iVgMLHb9uNWunfwjDU0mlECp6rp+occD5rm4k0XsmhUdYYDNB2N7vwL4ar7t7Y bRUrWcDXIDTzByGd1qZFeUPJ4XRuZmExIhm3XrLYrmbZvkYIH6oKzVv5knn9MHzzjsjfdiVDoME e2Bibk2Mj6F9ABYdpfXOcVNTMcGMZtsjvwmAv9Qx3j7PwTa5naJ0np9PriPDIM2jsshK4hOOa65 Z+fMEcQII52/5PTX5HX9sXBqn/ly0o9tU3LTzbR4GGVs6W1Rzk4Yoden9lVz+2Ti9QdMMMmqjSM hvdcZcYO8OTXRXZtW4dNPx1A4wMY6pfJadi3BaYatIPrJyHzova74Yk95MQNhaBqyh0DU= X-Mailer: git-send-email 2.42.0.515.g380fc7ccd1-goog Message-ID: <20230927224757.1154247-14-samitolvanen@google.com> Subject: [PATCH v4 6/6] lkdtm: Fix CFI_BACKWARD on RISC-V From: Sami Tolvanen To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Kees Cook Cc: Clement Leger , Guo Ren , Deepak Gupta , Nathan Chancellor , Nick Desaulniers , Fangrui Song , linux-riscv@lists.infradead.org, llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Sami Tolvanen Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" On RISC-V, the return address is before the current frame pointer, unlike on most other architectures. Use the correct offset on RISC-V to fix the CFI_BACKWARD test. Signed-off-by: Sami Tolvanen Acked-by: Kees Cook Tested-by: Nathan Chancellor --- drivers/misc/lkdtm/cfi.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c index fc28714ae3a6..6a33889d0902 100644 --- a/drivers/misc/lkdtm/cfi.c +++ b/drivers/misc/lkdtm/cfi.c @@ -68,12 +68,20 @@ static void lkdtm_CFI_FORWARD_PROTO(void) #define no_pac_addr(addr) \ ((__force __typeof__(addr))((uintptr_t)(addr) | PAGE_OFFSET)) =20 +#ifdef CONFIG_RISCV +/* https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-= cc.adoc#frame-pointer-convention */ +#define FRAME_RA_OFFSET (-1) +#else +#define FRAME_RA_OFFSET 1 +#endif + /* The ultimate ROP gadget. */ static noinline __no_ret_protection void set_return_addr_unchecked(unsigned long *expected, unsigned long *add= r) { /* Use of volatile is to make sure final write isn't seen as a dead store= . */ - unsigned long * volatile *ret_addr =3D (unsigned long **)__builtin_frame_= address(0) + 1; + unsigned long * volatile *ret_addr =3D + (unsigned long **)__builtin_frame_address(0) + FRAME_RA_OFFSET; =20 /* Make sure we've found the right place on the stack before writing it. = */ if (no_pac_addr(*ret_addr) =3D=3D expected) @@ -88,7 +96,8 @@ static noinline void set_return_addr(unsigned long *expected, unsigned long *addr) { /* Use of volatile is to make sure final write isn't seen as a dead store= . */ - unsigned long * volatile *ret_addr =3D (unsigned long **)__builtin_frame_= address(0) + 1; + unsigned long * volatile *ret_addr =3D + (unsigned long **)__builtin_frame_address(0) + FRAME_RA_OFFSET; =20 /* Make sure we've found the right place on the stack before writing it. = */ if (no_pac_addr(*ret_addr) =3D=3D expected) --=20 2.42.0.515.g380fc7ccd1-goog