From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754545Ab0FVGXO (ORCPT ); Tue, 22 Jun 2010 02:23:14 -0400 Received: from mga09.intel.com ([134.134.136.24]:20687 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754098Ab0FVGXN (ORCPT ); Tue, 22 Jun 2010 02:23:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.53,458,1272870000"; d="scan'208";a="632434083" Subject: [BUGFIX] kvm, Fix a race condition for usage of is_hwpoison_address From: Huang Ying To: Avi Kivity Cc: Andi Kleen , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Date: Tue, 22 Jun 2010 14:23:11 +0800 Message-ID: <1277187791.3004.149.camel@yhuang-dev.sh.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org is_hwpoison_address accesses the page table, so the caller must hold current->mm->mmap_sem in read mode. So fix its usage in hav_to_pfn of kvm accordingly. Comments on is_hwpoison_address are added to remind other users. Reported-by: Avi Kivity Signed-off-by: Huang Ying --- mm/memory-failure.c | 3 +++ virt/kvm/kvm_main.c | 3 ++- 2 files changed, 5 insertions(+), 1 deletion(-) --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1298,6 +1298,9 @@ done: return ret; } +/* + * The caller must hold current->mm->mmap_sem in read mode. + */ int is_hwpoison_address(unsigned long addr) { pgd_t *pgdp; --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -955,12 +955,13 @@ static pfn_t hva_to_pfn(struct kvm *kvm, if (unlikely(npages != 1)) { struct vm_area_struct *vma; + down_read(¤t->mm->mmap_sem); if (is_hwpoison_address(addr)) { + up_read(¤t->mm->mmap_sem); get_page(hwpoison_page); return page_to_pfn(hwpoison_page); } - down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, addr); if (vma == NULL || addr < vma->vm_start ||