From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:55972 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725751AbeKYCna (ORCPT ); Sat, 24 Nov 2018 21:43:30 -0500 Date: Sat, 24 Nov 2018 10:54:43 -0500 From: Sasha Levin To: "Kirill A. Shutemov" Cc: gregkh@linuxfoundation.org, tglx@linutronix.de, stable@vger.kernel.org Subject: Re: FAILED: patch "[PATCH] x86/ldt: Unmap PTEs for the slot before freeing LDT pages" failed to apply to 4.18-stable tree Message-ID: <20181124155443.GS1917@sasha-vm> References: <1542630273159205@kroah.com> <20181123115354.x5xzebiww3my4qie@black.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20181123115354.x5xzebiww3my4qie@black.fi.intel.com> Sender: stable-owner@vger.kernel.org List-ID: On Fri, Nov 23, 2018 at 02:53:54PM +0300, Kirill A. Shutemov wrote: >On Mon, Nov 19, 2018 at 12:24:33PM +0000, gregkh@linuxfoundation.org wrote: >> >> The patch below does not apply to the 4.18-stable tree. >> If someone wants it applied there, or to any other stable or longterm >> tree, then please email the backport, including the original git commit >> id to . > >>>From 13e702f756c72dc7c7f2d16920f3b31c9a154f8c Mon Sep 17 00:00:00 2001 >From: "Kirill A. Shutemov" >Date: Fri, 26 Oct 2018 15:28:55 +0300 >Subject: [PATCH 2/2] x86/ldt: Unmap PTEs for the slot before freeing LDT pages > >commit a0e6e0831c516860fc7f9be1db6c081fe902ebcf upstream > >modify_ldt(2) leaves the old LDT mapped after switching over to the new >one. The old LDT gets freed and the pages can be re-used. > >Leaving the mapping in place can have security implications. The mapping is >present in the userspace page tables and Meltdown-like attacks can read >these freed and possibly reused pages. > >It's relatively simple to fix: unmap the old LDT and flush TLB before >freeing the old LDT memory. > >This further allows to avoid flushing the TLB in map_ldt_struct() as the >slot is unmapped and flushed by unmap_ldt_struct() or has never been mapped >at all. > >[ tglx: Massaged changelog and removed the needless line breaks ] > >Fixes: f55f0501cbf6 ("x86/pti: Put the LDT in its own PGD if PTI is on") >Signed-off-by: Kirill A. Shutemov >Signed-off-by: Thomas Gleixner >Cc: bp@alien8.de >Cc: hpa@zytor.com >Cc: dave.hansen@linux.intel.com >Cc: luto@kernel.org >Cc: peterz@infradead.org >Cc: boris.ostrovsky@oracle.com >Cc: jgross@suse.com >Cc: bhe@redhat.com >Cc: willy@infradead.org >Cc: linux-mm@kvack.org >Cc: stable@vger.kernel.org >Link: https://lkml.kernel.org/r/20181026122856.66224-3-kirill.shutemov@linux.intel.com Queued for 4.18, thank you. -- Thanks, Sasha