From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36858 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933202AbcFLVf6 (ORCPT ); Sun, 12 Jun 2016 17:35:58 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ingo Molnar" , "Jan Beulich" , "Borislav Petkov" , "Denys Vlasenko" , "Luis R. Rodriguez" , "Peter Zijlstra" , "David Vrabel" , "Brian Gerst" , "Thomas Gleixner" , "Juergen Gross" , "Vitaly Kuznetsov" , "Andy Lutomirski" , "Linus Torvalds" , "H. Peter Anvin" , "Jan Beulich" , "Boris Ostrovsky" , "Toshi Kani" , "xen-devel" Date: Sun, 12 Jun 2016 22:34:42 +0100 Message-ID: Subject: [PATCH 3.2 24/46] x86/mm/xen: Suppress hugetlbfs in PV guests In-Reply-To: Sender: stable-owner@vger.kernel.org List-ID: 3.2.81-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Jan Beulich commit 103f6112f253017d7062cd74d17f4a514ed4485c upstream. Huge pages are not normally available to PV guests. Not suppressing hugetlbfs use results in an endless loop of page faults when user mode code tries to access a hugetlbfs mapped area (since the hypervisor denies such PTEs to be created, but error indications can't be propagated out of xen_set_pte_at(), just like for various of its siblings), and - once killed in an oops like this: kernel BUG at .../fs/hugetlbfs/inode.c:428! invalid opcode: 0000 [#1] SMP ... RIP: e030:[] [] remove_inode_hugepages+0x25b/0x320 ... Call Trace: [] hugetlbfs_evict_inode+0x15/0x40 [] evict+0xbd/0x1b0 [] __dentry_kill+0x19a/0x1f0 [] dput+0x1fe/0x220 [] __fput+0x155/0x200 [] task_work_run+0x60/0xa0 [] do_exit+0x160/0x400 [] do_group_exit+0x3b/0xa0 [] get_signal+0x1ed/0x470 [] do_signal+0x14/0x110 [] prepare_exit_to_usermode+0xe9/0xf0 [] retint_user+0x8/0x13 This is CVE-2016-3961 / XSA-174. Reported-by: Vitaly Kuznetsov Signed-off-by: Jan Beulich Cc: Andrew Morton Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: David Vrabel Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Juergen Gross Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Cc: xen-devel Link: http://lkml.kernel.org/r/57188ED802000078000E431C@prv-mh.provo.novell.com Signed-off-by: Ingo Molnar Signed-off-by: Ben Hutchings --- arch/x86/include/asm/hugetlb.h | 1 + 1 file changed, 1 insertion(+) --- a/arch/x86/include/asm/hugetlb.h +++ b/arch/x86/include/asm/hugetlb.h @@ -3,6 +3,7 @@ #include +#define hugepages_supported() cpu_has_pse static inline int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,