From nobody Fri Dec 19 14:38:17 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 7ED6EC83F1A for ; Mon, 28 Aug 2023 19:59:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233612AbjH1T7a (ORCPT ); Mon, 28 Aug 2023 15:59:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233544AbjH1T6w (ORCPT ); Mon, 28 Aug 2023 15:58:52 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AEA8F188 for ; Mon, 28 Aug 2023 12:58:49 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id 41be03b00d2f7-56fe210b7edso2222289a12.0 for ; Mon, 28 Aug 2023 12:58:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1693252729; x=1693857529; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=BqxXsJhK/PDnu5QKzOuhVQVuGBQ7YV59awRNcw8M9KA=; b=5vbcngL8ZVHRFE2eljBR/WQoqnwHuLVs7upb4C37eJWQbZVjr56f/ur647yJ4AUyqU odlSa8/RjIkDV07G0UBaBb4auy8DU4amPuju8M5IQqLJYH54J4qila2NhRd+E1O4RyAM uVYOKvozn6NT8UEW8VWKOZJe/DKWNoXAIn9cnQYVR4AleyEg1/b63QvqUxI0dcSLbnMx XLuUylSfyiMonef/eNWAAMq+tnS4EWsKMBu8wIhTW3R0YLJ6tJf56CDFzDgaITSCuq+s BLuYHuv7RfEgVzf9k8LBhuxRvd2HXWmtf2Vk/OTijRK93Crc/qqwJGPUvgiTw7PzvnTZ ll/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693252729; x=1693857529; 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=BqxXsJhK/PDnu5QKzOuhVQVuGBQ7YV59awRNcw8M9KA=; b=TF4mSj2Y4xjw+L8/RPckBSebxa9rWcYXh7RF+PNvfLCWAdD3ZpQ03CIM2KGPVVEl5v xaEjYX31LADPesxNxRSpXF1DnXlYCJaWTlsPfNB3qhzKHBbvYYSif8SxlHCeueliCXQd 38AvA/zQYH+38xp3GRcSSFa/Ul2KdoFhTQdxvaTWlV/LUeqPcNWWxmBj156MwTaNsBKz XFru4oHH7qHzcxNGoXNIWxBrpi2j7OaDZYtboB4dVhJiiaqUMNiKRo2VhAKvNsHHKIxO wB2ROiWeIFFVa0wgRT5fHJ28gUU/Ys/Ss4zdnSPkA9ik1ul0DGsMG1QR7SZ0hg8TmVky pXnw== X-Gm-Message-State: AOJu0YwZFW40w7Bd1lh5I6Cq95veQwD4Yvgt4G+gHs0UZXd6qTAoJiqX J8NmAUzqBTy2qDNKLJbKGP7Lu6DhegrJVOjrRJ8= X-Google-Smtp-Source: AGHT+IFGsaaO0XSM/Y67KiglbiGwn9oCum6xrnQEFf9Pggoc6RCuQ0rJ2Xb5U12wKvaEKKMsCRfVVSyEDOKWowHVSW0= X-Received: from samitolvanen.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:4f92]) (user=samitolvanen job=sendgmr) by 2002:a63:9351:0:b0:569:52d4:fb68 with SMTP id w17-20020a639351000000b0056952d4fb68mr2368998pgm.5.1693252729217; Mon, 28 Aug 2023 12:58:49 -0700 (PDT) Date: Mon, 28 Aug 2023 19:58:40 +0000 In-Reply-To: <20230828195833.756747-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20230828195833.756747-8-samitolvanen@google.com> X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=2086; i=samitolvanen@google.com; h=from:subject; bh=P2l56HkzVV4iJDbhsS59ZlfJgm96l/buqsb6+trKTfA=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBk7PxqKl9k+yTdNALVx1ZMSiIiYkPp3ifD0Ueug LDeD+59dp2JAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCZOz8agAKCRBMtfaEi7xW 7ombC/44I2N+oNE0mhFWTI0lDlgL+4/JMQhfMKSufRM3U1T5OqabvtPwFHQhOXRz1TiwEcDr7i8 5yQiZuqOXgg3iZ4h+9F4cRzw28ArehJIEGz+O7FO70FgOBNXOSHaWGcyv7VuHdprWhST+C1v9Zk ZgslARn9fBw5HJwmwr6bN8M9im4r9jKtVsPr55L3xnUWbk+knu12/aZpE/GGE0bbf3QK+N4vt3A 0nNh0iiFlV4YayOAPFabrTDShrkvvWlE4rzF+fG11hd/h8APu37zoH57B2AywUWNj14p83mXT6k u9y2x57j40yu0iK/b1JflZvDK7CJ0s8ajtQhMOXhjDmApgyeWZVLMLAZTpKv4gs/oO2xodXiw4R ksl1GmDHjdIlhyeMTWWtCCcg/DIiAd6f1B740jP4kkXUDiP9Sy3P/G0MHt1K+RGieGHpaB5B13/ UvPppmx2PeR8h40O/fHIATSyyElr9SQ8Dg84t2Fd6nUgiqKsWp+OrKSdL0qF6hmaWxQ0o= X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-goog Message-ID: <20230828195833.756747-14-samitolvanen@google.com> Subject: [PATCH v3 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.rc2.253.gd59a3bf2b4-goog