From nobody Sun Feb 8 17:41:33 2026 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 63BA9EB64D8 for ; Fri, 16 Jun 2023 19:18:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232773AbjFPTSt (ORCPT ); Fri, 16 Jun 2023 15:18:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48122 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345964AbjFPTRF (ORCPT ); Fri, 16 Jun 2023 15:17:05 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 773BA3AA8; Fri, 16 Jun 2023 12:17:02 -0700 (PDT) Date: Fri, 16 Jun 2023 19:17:00 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1686943021; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ha6EPbpdA+l2JvEFyPXLUG/lmSuPF5IVCR6oMWi+6aE=; b=AzMxja+4zsMRcfC4Uct3im7qjKUzVlbhKhmpkve29Na1OOY2JgQCxGDUnRd7xqgT11P50m WpoSnrhboOcLG1nsSQsn4m2kHIOawKtZbon3y4mPkjTEAHOXBy2onCsWg3bDITrtUM1qcS bEHABDyCd2/zpjtypOvPrkiPzk9rKDOkX49VA9xmmmgr7hR1XBZc0LEzShX8RGlUs2wnDB 8kozN8yQGmniMwmkIoqAYIXFhMhM7LQiCQLPTR149O2sFdCjhqb6Fm3to8BqFu7m8N6UZ6 8xtzl/wUUX8zYo5klwuezQN7ewzRHpwiB/MWU3xY/Ur8w7Zqi+VMQqQg+CuQ1w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1686943021; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=ha6EPbpdA+l2JvEFyPXLUG/lmSuPF5IVCR6oMWi+6aE=; b=aUO0pCWI9NuzL2r4PvnTFeLDF+VcpKJQsszr3aT/qmH6+FTfzyHdR81V4drJves9SAsQe1 Mvfw0uHP46BeGZAQ== From: "tip-bot2 for Rick Edgecombe" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/shstk] x86/mm: Warn if create Write=0,Dirty=1 with raw prot Cc: Rick Edgecombe , Dave Hansen , Pengfei Xu , John Allen , Kees Cook , x86@kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Message-ID: <168694302063.404.5940870188283668995.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/shstk branch of tip: Commit-ID: ea7e66f02cbf4f025b95cd724e2159dfdec16464 Gitweb: https://git.kernel.org/tip/ea7e66f02cbf4f025b95cd724e2159dfd= ec16464 Author: Rick Edgecombe AuthorDate: Mon, 12 Jun 2023 17:10:44 -07:00 Committer: Dave Hansen CommitterDate: Thu, 15 Jun 2023 16:31:33 -07:00 x86/mm: Warn if create Write=3D0,Dirty=3D1 with raw prot When user shadow stack is in use, Write=3D0,Dirty=3D1 is treated by the CPU= as shadow stack memory. So for shadow stack memory this bit combination is valid, but when Dirty=3D1,Write=3D1 (conventionally writable) memory is bei= ng write protected, the kernel has been taught to transition the Dirty=3D1 bit to SavedDirty=3D1, to avoid inadvertently creating shadow stack memory. It does this inside pte_wrprotect() because it knows the PTE is not intended to be a writable shadow stack entry, it is supposed to be write protected. However, when a PTE is created by a raw prot using mk_pte(), mk_pte() can't know whether to adjust Dirty=3D1 to SavedDirty=3D1. It can't distinguish between the caller intending to create a shadow stack PTE or needing the SavedDirty shift. The kernel has been updated to not do this, and so Write=3D0,Dirty=3D1 memory should only be created by the pte_mkfoo() helpers. Add a warning to make sure no new mk_pte() start doing this, like, for example, set_memory_rox() did. Signed-off-by: Rick Edgecombe Signed-off-by: Dave Hansen Tested-by: Pengfei Xu Tested-by: John Allen Tested-by: Kees Cook Link: https://lore.kernel.org/all/20230613001108.3040476-19-rick.p.edgecomb= e%40intel.com --- arch/x86/include/asm/pgtable.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 3fbddf6..e846f0c 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1032,7 +1032,14 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) * (Currently stuck as a macro because of indirect forward reference * to linux/mm.h:page_to_nid()) */ -#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot)) +#define mk_pte(page, pgprot) \ +({ \ + pgprot_t __pgprot =3D pgprot; \ + \ + WARN_ON_ONCE((pgprot_val(__pgprot) & (_PAGE_DIRTY | _PAGE_RW)) =3D=3D \ + _PAGE_DIRTY); \ + pfn_pte(page_to_pfn(page), __pgprot); \ +}) =20 static inline int pmd_bad(pmd_t pmd) {