From nobody Thu Dec 18 07:58:06 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 3D4A0C04FDF for ; Tue, 15 Aug 2023 20:35:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238279AbjHOUfQ (ORCPT ); Tue, 15 Aug 2023 16:35:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238074AbjHOUe6 (ORCPT ); Tue, 15 Aug 2023 16:34:58 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5410F7 for ; Tue, 15 Aug 2023 13:34:57 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id d2e1a72fcca58-686b879f630so6261875b3a.3 for ; Tue, 15 Aug 2023 13:34:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1692131697; x=1692736497; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=0Ykk2Dcm0sp1r3wFF3O+L+QDwz/a2RXVAzUE310xTCE=; b=c51n2/tJShODyeeUWChM6SNmOtBH4TwAB27gHlz0U2MW1KhJAFsJAI7HodLDVzEs2L h5EacJeK3yQ7xI1bDM7pS/8+NTTnu/pBkkf0mHnOLxusk130BgOMc3UgF/ILE4pTCv3b FoK/mdVbDTdzIm+PesccCvkjIraV3wLcVysrd2PMSHMHQsQbcViexWNnSAbHE6yrDtgT Mp+VyMCTaEctp9R1ryTin05vgD7DzxczuWzmHabxbBnipkxhOH1Z8NXKF+B+bk3ZWN2C pzEoTOjVu6w2TWjI1tCV+5ZHtdXlLljOrV5rvKK0dr/ZGKr7YBnabTma9ayXOLsdZ9cs ecvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692131697; x=1692736497; 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=0Ykk2Dcm0sp1r3wFF3O+L+QDwz/a2RXVAzUE310xTCE=; b=BlmY6QCqYTOVoTzRIUih1vAU+GtmuIDD3WRbT9Xf/TE5VZF5RyI5KKlQiJzRa4fQVJ sds44cSIxSWyL7mIuD9bGrmqCC/b+MuM4Bo3+jQjKl+dhD1XGrK+48C3t3Xo5ATfEOvW NuBSgeC0Ny5AWK0StTMUSKYpw8GhRltx/yXNW5X8QmC2i3c6isCHS2sCaPSmmaKV1jUJ 7IGbaGvtrLxAlNaiKhWXVVSiVGJQ4ybL6l9rSQyCv/laD0k3MY6NRP6Q2naCFVTGCb9y H5oSeLEk5TCjv8TitlPikfOy2lqxTvtNWlZHCrJMeHwLhD4d9qyMNJP+BO8kK3srmE40 auWw== X-Gm-Message-State: AOJu0YxblDjB3CEYKl11Pdo/7tSC7u9/qcOfocaLWlHYX6FTjDQMco41 7zWK+dfFHSf3Iub+Ui6lVoyuCps4JbYLrlh3BbE= X-Google-Smtp-Source: AGHT+IFSPEKlQSmP4El45E8vBc0Epq9faMbNSeZpAP4jMdZu51DXHIvs320ofYVLaVzWyPCFTx03x5OLJ9JW1V1TgBQ= X-Received: from samitolvanen.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:4f92]) (user=samitolvanen job=sendgmr) by 2002:a05:6a00:1a87:b0:674:1663:1270 with SMTP id e7-20020a056a001a8700b0067416631270mr6012423pfv.4.1692131697326; Tue, 15 Aug 2023 13:34:57 -0700 (PDT) Date: Tue, 15 Aug 2023 20:34:49 +0000 In-Reply-To: <20230815203442.1608773-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20230815203442.1608773-8-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=1987; i=samitolvanen@google.com; h=from:subject; bh=ki2ulz3S+Qkr8AIV7YWzX5sRx6qIOMgf7DcUTP9c/kA=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBk2+Fi+17Bq1AKxHm6SJ6quZHGmn+eubZLGDQWv bi76aScYZaJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCZNvhYgAKCRBMtfaEi7xW 7uDxC/4yeVJIZQGthB7VhCrB1mQ9aPlWa4zl/qPRC5GlncPWQV/MwLuo1ExhOVxQY1M+pu82F+m 8PqQG33dyzALoBf1c1t0RJgk8hXrSg+on+5gsx856SahKsjV3+GpMyptJgjPEwnNHk+6wKMMK8A N/pPZs3mhzf+AhJROOGKLcZi1Ux1G5qizF4mL1TsJXLT2ky85P+u9iE+XnlUUOVj0o6+zdRc6E4 T3hgbyVAvct21OxraGNq6gZ4hFfI1gD0Vzy9TsNhYvkKUv6h9A3mjyabLDgnWYIneyLL5Aw8hLM 778p+uRcOJ4tKxAH+wveS7E7YVuTsPIR0MtZTeW4TlXWx284O7O/LdzF0u0artPihMYgdyyeXkT fbWExG0nGe0BC399mEX2b1gOK/3yeNpSy5DzlUGN+aTa7vNStcHxmPR4yr6Qlfw7uDrg4g305Ra AkJHJ/qsdN+6PCM8BiYrPK7icqJ3WmLfwFC54pjnKI93e+BJiBx3TlG5aczelxjKucC60= X-Mailer: git-send-email 2.41.0.694.ge786442a9b-goog Message-ID: <20230815203442.1608773-14-samitolvanen@google.com> Subject: [PATCH v2 6/6] lkdtm: Fix CFI_BACKWARD on RISC-V From: Sami Tolvanen To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Kees Cook Cc: 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 --- 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 2.41.0.694.ge786442a9b-goog