From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753085Ab2IPRvA (ORCPT ); Sun, 16 Sep 2012 13:51:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40300 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753008Ab2IPRu4 (ORCPT ); Sun, 16 Sep 2012 13:50:56 -0400 Date: Sun, 16 Sep 2012 19:52:48 +0200 From: Oleg Nesterov To: Ingo Molnar , Peter Zijlstra , Srikar Dronamraju Cc: Ananth N Mavinakayanahalli , Anton Arapov , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org Subject: [PATCH 3/3] uprobes: Restrict valid_vma(false) to skip VM_SHARED Message-ID: <20120916175248.GA32373@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120916175210.GA32337@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org valid_vma(false) ignores ->vm_flags, this is not actually right. We should never try to write into MAP_SHARED mapping, this can confuse an apllication which actually writes to ->vm_file. With this patch valid_vma(false) ignores VM_WRITE only but checks other (immutable) bits checked by valid_vma(true). This can also speedup uprobe_munmap() and uprobe_unregister(). Note: even after this patch _unregister can confuse the probed application if it does mprotect(PROT_WRITE) after _register and installs "int3", but this is hardly possible to avoid and this doesn't differ from gdb case. Signed-off-by: Oleg Nesterov --- kernel/events/uprobes.c | 13 ++++--------- 1 files changed, 4 insertions(+), 9 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index b9b50dd..78364a2 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -100,17 +100,12 @@ struct uprobe { */ static bool valid_vma(struct vm_area_struct *vma, bool is_register) { - if (!vma->vm_file) - return false; - - if (!is_register) - return true; + vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; - if ((vma->vm_flags & (VM_HUGETLB | VM_WRITE | VM_MAYEXEC | VM_SHARED)) - == VM_MAYEXEC) - return true; + if (is_register) + flags |= VM_WRITE; - return false; + return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; } static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) -- 1.5.5.1