From nobody Thu Sep 11 12:48:50 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 BFC8BC04A6A for ; Thu, 3 Aug 2023 15:16:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236283AbjHCPQg (ORCPT ); Thu, 3 Aug 2023 11:16:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234544AbjHCPQd (ORCPT ); Thu, 3 Aug 2023 11:16:33 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0066E77 for ; Thu, 3 Aug 2023 08:16:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1691075792; x=1722611792; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=/nVvtIp70+FSePc0879BDHNt5uW/EgkRqUTXM82sSno=; b=cWDWhnC3OUokidSSVHBK2/I17p1Wb/lbBqa19EnWSBqGTAvx4YZ2D2hg DvF4DKUSZ9qsQLcDKoo1al3AmKC5etHwlU7s2qcMXFaFbwhsLLaW7fLMQ SkaC3MSm1Wt84EUZdqQI9pqUJZaxmx2cVvO7Vch4B4bKOgXe4/QFtTkRl orujQH4R6J5wjWWhlQcbyZOc+kFtUYcpo6F2gHBpXJI5J7XG5yyFu5Lgj WLQzmCT3Mb5LeMJn0MD7YNl/Lf0ZP9Rg0T264rxMlZqaxZuFYa1QVvb9c 1mgvZ3ogPPmk59G69vMZjapI0GqNzSx+JGcriMnvMEAIRdIa+8+kCu+5Z A==; X-IronPort-AV: E=McAfee;i="6600,9927,10791"; a="354833962" X-IronPort-AV: E=Sophos;i="6.01,252,1684825200"; d="scan'208";a="354833962" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Aug 2023 08:16:32 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10791"; a="903418183" X-IronPort-AV: E=Sophos;i="6.01,252,1684825200"; d="scan'208";a="903418183" Received: from sosterlu-mobl1.ger.corp.intel.com (HELO box.shutemov.name) ([10.251.209.233]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Aug 2023 08:16:18 -0700 Received: by box.shutemov.name (Postfix, from userid 1000) id CBB2E109FCF; Thu, 3 Aug 2023 18:16:13 +0300 (+03) From: "Kirill A. Shutemov" To: dave.hansen@intel.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de Cc: x86@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Yingcong Wu Subject: [PATCHv2] x86/mm: Fix VDSO and VVAR placement on 5-level paging machines Date: Thu, 3 Aug 2023 18:16:09 +0300 Message-ID: <20230803151609.22141-1-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Yingcong has noticed that on the 5-level paging machine, VDSO and VVAR VMAs are placed above the 47-bit border: 8000001a9000-8000001ad000 r--p 00000000 00:00 0 [v= var] 8000001ad000-8000001af000 r-xp 00000000 00:00 0 [v= dso] This might confuse users who are not aware of 5-level paging and expect all userspace addresses to be under the 47-bit border. So far problem has only been triggered with ASLR disabled, although it may also occur with ASLR enabled if the layout is randomized in a just right way. The problem happens due to custom placement for the VMAs in the VDSO code: vdso_addr() tries to place them above the stack and checks the result against TASK_SIZE_MAX, which is wrong. TASK_SIZE_MAX is set to the 56-bit border on 5-level paging machines. Use DEFAULT_MAP_WINDOW instead. Signed-off-by: Kirill A. Shutemov Reported-by: Yingcong Wu Fixes: b569bab78d8d ("x86/mm: Prepare to expose larger address space to use= rspace") Reviewed-by: Rick Edgecombe --- v2: - Fix commit message: grammar and passive voice arch/x86/entry/vdso/vma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 11a5c68d1218..7645730dc228 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -299,8 +299,8 @@ static unsigned long vdso_addr(unsigned long start, uns= igned len) =20 /* Round the lowest possible end address up to a PMD boundary. */ end =3D (start + len + PMD_SIZE - 1) & PMD_MASK; - if (end >=3D TASK_SIZE_MAX) - end =3D TASK_SIZE_MAX; + if (end >=3D DEFAULT_MAP_WINDOW) + end =3D DEFAULT_MAP_WINDOW; end -=3D len; =20 if (end > start) { --=20 2.41.0