From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752191AbbAMM1M (ORCPT ); Tue, 13 Jan 2015 07:27:12 -0500 Received: from smtp.codeaurora.org ([198.145.11.231]:52149 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751046AbbAMM1K (ORCPT ); Tue, 13 Jan 2015 07:27:10 -0500 From: Shiraz Hashim To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, oleg@redhat.com, gorcunov@openvz.org, linux-kernel@vger.kernel.org, Shiraz Hashim Subject: [PATCH 1/1] mm: pagemap: limit scan to virtual region being asked Date: Tue, 13 Jan 2015 17:57:04 +0530 Message-Id: <1421152024-6204-1-git-send-email-shashim@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org pagemap_read scans through the virtual address space of a task till it prepares 'count' pagemaps or it reaches end of task. This presents a problem when the page walk doesn't happen for vma with VM_PFNMAP set. In which case walk is silently skipped and no pagemap is prepare, in turn making pagemap_read to scan through task end, even crossing beyond 'count', landing into a different vma region. This leads to wrong presentation of mappings for that vma. Fix this by limiting end_vaddr to the end of the virtual address region being scanned. Signed-off-by: Shiraz Hashim --- fs/proc/task_mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 246eae8..04362e4 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1270,7 +1270,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, src = *ppos; svpfn = src / PM_ENTRY_BYTES; start_vaddr = svpfn << PAGE_SHIFT; - end_vaddr = TASK_SIZE_OF(task); + end_vaddr = start_vaddr + ((count / PM_ENTRY_BYTES) << PAGE_SHIFT); + if ((end_vaddr > TASK_SIZE_OF(task)) || (end_vaddr < start_vaddr)) + end_vaddr = TASK_SIZE_OF(task); /* watch out for wraparound */ if (svpfn > TASK_SIZE_OF(task) >> PAGE_SHIFT) -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation