From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by kanga.kvack.org (Postfix) with ESMTP id 258608E0001 for ; Mon, 17 Sep 2018 15:34:07 -0400 (EDT) Received: by mail-pl1-f200.google.com with SMTP id w11-v6so8126225plq.8 for ; Mon, 17 Sep 2018 12:34:07 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id d29-v6sor2509973pfj.97.2018.09.17.12.34.05 for (Google Transport Security); Mon, 17 Sep 2018 12:34:05 -0700 (PDT) Date: Mon, 17 Sep 2018 12:33:47 -0700 (PDT) From: Hugh Dickins Subject: Re: Patch "x86/kexec: Allocate 8k PGDs for PTI" has been added to the 3.18-stable tree In-Reply-To: <1537177617126129@kroah.com> Message-ID: References: <1537177617126129@kroah.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: gregkh@linuxfoundation.org Cc: 1532533683-5988-4-git-send-email-joro@8bytes.org, David.Laight@aculab.com, aarcange@redhat.com, acme@kernel.org, alexander.levin@microsoft.com, alexander.shishkin@linux.intel.com, aliguori@amazon.com, boris.ostrovsky@oracle.com, bp@alien8.de, brgerst@gmail.com, daniel.gruss@iaik.tugraz.at, dave.hansen@intel.com, dhgutteridge@sympatico.ca, dvlasenk@redhat.com, eduval@amazon.com, hpa@zytor.com, hughd@google.com, jgross@suse.com, jkosina@suse.cz, jolsa@redhat.comjoro@8bytes.org, jpoimboe@redhat.com, jroedel@suse.de, keescook@google.com, linux-mm@kvack.org, llong@redhat.com, luto@kernel.org, namhyung@kernel.org, pavel@ucw.cz, peterz@infradead.org, tglx@linutronix.de, torvalds@linux-foundation.org, will.deacon@arm.com, stable-commits@vger.kernel.org, stable@vger.kernel.org On Mon, 17 Sep 2018, gregkh@linuxfoundation.org wrote: > > This is a note to let you know that I've just added the patch titled > > x86/kexec: Allocate 8k PGDs for PTI > > to the 3.18-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > x86-kexec-allocate-8k-pgds-for-pti.patch > and it can be found in the queue-3.18 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let know about it. I believe this commit is an example of the auto-selector being too eager, and this should not be in *any* of the stable trees. As the commit message indicates, it's a fix by Joerg for his PTI-x86-32 implementation - which has not been backported to any of the stable trees (yet), has it? In several of the recent stable trees, I think this will not do any actual harm; but it looks as if it will prevent relevant x86-32 configs from building on 3.18 (I see no definition of PGD_ALLOCATION_ORDER in linux-3.18.y - you preferred not to have any PTI in that tree), and I haven't checked whether its definition in older backports will build correctly here or not. Hugh > > > From foo@baz Mon Sep 17 11:45:57 CEST 2018 > From: Joerg Roedel > Date: Wed, 25 Jul 2018 17:48:03 +0200 > Subject: x86/kexec: Allocate 8k PGDs for PTI > > From: Joerg Roedel > > [ Upstream commit ca38dc8f2724d101038b1205122c93a1c7f38f11 ] > > Fuzzing the PTI-x86-32 code with trinity showed unhandled > kernel paging request oops-messages that looked a lot like > silent data corruption. > > Lot's of debugging and testing lead to the kexec-32bit code, > which is still allocating 4k PGDs when PTI is enabled. But > since it uses native_set_pud() to build the page-table, it > will unevitably call into __pti_set_user_pgtbl(), which > writes beyond the allocated 4k page. > > Use PGD_ALLOCATION_ORDER to allocate PGDs in the kexec code > to fix the issue. > > Signed-off-by: Joerg Roedel > Signed-off-by: Thomas Gleixner > Tested-by: David H. Gutteridge > Cc: "H . Peter Anvin" > Cc: linux-mm@kvack.org > Cc: Linus Torvalds > Cc: Andy Lutomirski > Cc: Dave Hansen > Cc: Josh Poimboeuf > Cc: Juergen Gross > Cc: Peter Zijlstra > Cc: Borislav Petkov > Cc: Jiri Kosina > Cc: Boris Ostrovsky > Cc: Brian Gerst > Cc: David Laight > Cc: Denys Vlasenko > Cc: Eduardo Valentin > Cc: Greg KH > Cc: Will Deacon > Cc: aliguori@amazon.com > Cc: daniel.gruss@iaik.tugraz.at > Cc: hughd@google.com > Cc: keescook@google.com > Cc: Andrea Arcangeli > Cc: Waiman Long > Cc: Pavel Machek > Cc: Arnaldo Carvalho de Melo > Cc: Alexander Shishkin > Cc: Jiri Olsa > Cc: Namhyung Kim > Cc: joro@8bytes.org > Link: https://lkml.kernel.org/r/1532533683-5988-4-git-send-email-joro@8bytes.org > Signed-off-by: Sasha Levin > Signed-off-by: Greg Kroah-Hartman > --- > arch/x86/kernel/machine_kexec_32.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > --- a/arch/x86/kernel/machine_kexec_32.c > +++ b/arch/x86/kernel/machine_kexec_32.c > @@ -69,7 +69,7 @@ static void load_segments(void) > > static void machine_kexec_free_page_tables(struct kimage *image) > { > - free_page((unsigned long)image->arch.pgd); > + free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER); > image->arch.pgd = NULL; > #ifdef CONFIG_X86_PAE > free_page((unsigned long)image->arch.pmd0); > @@ -85,7 +85,8 @@ static void machine_kexec_free_page_tabl > > static int machine_kexec_alloc_page_tables(struct kimage *image) > { > - image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL); > + image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, > + PGD_ALLOCATION_ORDER); > #ifdef CONFIG_X86_PAE > image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL); > image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL); > > > Patches currently in stable-queue which might be from jroedel@suse.de are > > queue-3.18/x86-kexec-allocate-8k-pgds-for-pti.patch > queue-3.18/x86-mm-remove-in_nmi-warning-from-vmalloc_fault.patch >