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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F74DEB64D8 for ; Wed, 14 Jun 2023 16:39:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 181166B0081; Wed, 14 Jun 2023 12:39:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1313A6B0082; Wed, 14 Jun 2023 12:39:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 020008E0001; Wed, 14 Jun 2023 12:39:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id E67CE6B0081 for ; Wed, 14 Jun 2023 12:39:32 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id B8054402EB for ; Wed, 14 Jun 2023 16:39:32 +0000 (UTC) X-FDA: 80901914184.06.13E0EAF Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf19.hostedemail.com (Postfix) with ESMTP id E777A1A0004 for ; Wed, 14 Jun 2023 16:39:30 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=a5eEFKOn; spf=pass (imf19.hostedemail.com: domain of lee@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=lee@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1686760771; a=rsa-sha256; cv=none; b=AzhoRaB8PbzakfbIMjbabZqPuaYFTaerDhbsw/BOKfzT5ZvWmZm8ENXe7chAPSXy4oKpK6 78hICEj/aNqj9YFizTD/mHmLifiLClngZhu7x7oRX1s17cPXhTxFZ4TnJ4ERdITVEjDIhQ vzG3Z9luulqUsAFwThe37oKySdkTAnU= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=a5eEFKOn; spf=pass (imf19.hostedemail.com: domain of lee@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=lee@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1686760771; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=JpotcZvu92R1QGWTXDbnByx0mcrSCDcuvxrJiTLzyTw=; b=Wsoqi6NtIYBxyg3mIWiAIp6k+fXlih3O8vOrYlL1bwplGhw6OVoQsOkxUJhFDhy+Um+3Td FUtz2a5k4cYmqSU2aT8nkxWPlWxDHkgDeklKF6A23pjYZerA53eC6jF6skkV89aRznKQHx 1PVkdSQZlfqnie9UnDlMRX18wnpGI/E= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EB3106449B; Wed, 14 Jun 2023 16:39:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6CCEC433BB; Wed, 14 Jun 2023 16:39:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686760769; bh=CiaATWA3DUiAf96JCsvwKvujvWjgKxROvf/tLbnTMT4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a5eEFKOn/oJfksLkjOkh0XikxN/2rxRKsth1fo3Humda0sRF+XcIdTsOZHltbnEke r0uXSJB7JvDMGlTDGHZZ5A4YvieVJlgRBk7kMIQ0r6yalVxy77ojfomI4lnjrWNFh9 YLFBZ22E+kL4iw076ctEAqgZmHczLccQpVW0eheI1eKqiy8Ln5kVI1RicBtxeYoXcW F5r0mILjCM+2solcJ8PvMXSY1hWIfAo1sKCqHSCvQkYEKHc21zWwvfXPp2BH9vz9bH HuNCLANCAbHcbtzKuPurXHPvhkuBnB57YIqPQLa/MvGZlCkxEuWnuW8IH6JihQ8R7G QLGqaIQ8dvEyA== From: Lee Jones To: lee@kernel.org, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Subject: [PATCH v2 1/1] x86/mm/KASLR: Store pud_page_tramp into entry rather than page Date: Wed, 14 Jun 2023 17:38:54 +0100 Message-ID: <20230614163859.924309-2-lee@kernel.org> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog In-Reply-To: <20230614163859.924309-1-lee@kernel.org> References: <20230614163859.924309-1-lee@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: E777A1A0004 X-Stat-Signature: w8smk919msjm6fod8oze1a3b4zj9jm4j X-Rspam-User: X-HE-Tag: 1686760770-433993 X-HE-Meta: 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 M5o05jOu CQSLVz/esEh0YNZXDd84p+aYVobJKjjmCZQ6eUlVAmAE8IUfy3g7TKevP6QFBSqwCD4h09PS9T9zP7FH2Lsu2i0fQeyCzNUmbdP2YVsECbjxg+RNOypMW+nRMwGdYgpSoxFvE6IC0hLLXxU+uZ0N6DlIG8/alcEFdyAvu+xHCJS/UbEwGF9ZLsK82xTDwTLwt7yixl28s9N5UUbCmQ+ZiDy2j4zJqHB2qfpsF9qtX9jh9rwSqFIP/RBnQOsHB2h9izYNNM/nbE9r8r+MFYLJwn8yvfYTW8+C5T60BIiXigFD+d/zzsnLnKGonFsPWobZe6aHPyQNm6xBQG7rcIEHjUhVdO7uF8WdqYIDTKeM0xIO6CzsTL29ohO4e5YH5F9J83tOxN3CnSyD+cw91MAi5PCIGDA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: set_pgd() expects to be passed whole pages to operate on, whereas trampoline_pgd_entry is, as the name suggests, an entry. The ramifications for using set_pgd() here are that the following thread of execution will not only place the suggested value into the trampoline_pgd_entry (8-Byte globally stored [.bss]) variable, PTI will also attempt to replicate that value into the non-existent neighboring user page (located +4k away), leading to the corruption of other global [.bss] stored variables. Suggested-by: Dave Hansen Signed-off-by: Lee Jones --- arch/x86/mm/kaslr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c index 557f0fe25dff4..37db264866b64 100644 --- a/arch/x86/mm/kaslr.c +++ b/arch/x86/mm/kaslr.c @@ -172,10 +172,10 @@ void __meminit init_trampoline_kaslr(void) set_p4d(p4d_tramp, __p4d(_KERNPG_TABLE | __pa(pud_page_tramp))); - set_pgd(&trampoline_pgd_entry, - __pgd(_KERNPG_TABLE | __pa(p4d_page_tramp))); + trampoline_pgd_entry = + __pgd(_KERNPG_TABLE | __pa(p4d_page_tramp)); } else { - set_pgd(&trampoline_pgd_entry, - __pgd(_KERNPG_TABLE | __pa(pud_page_tramp))); + trampoline_pgd_entry = + __pgd(_KERNPG_TABLE | __pa(pud_page_tramp)); } } -- 2.41.0.162.gfafddb0af9-goog