From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758281Ab2CMASE (ORCPT ); Mon, 12 Mar 2012 20:18:04 -0400 Received: from mail.windriver.com ([147.11.1.11]:46783 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758245Ab2CMASA (ORCPT ); Mon, 12 Mar 2012 20:18:00 -0400 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Linus Torvalds , Paul Gortmaker Subject: [34-longterm 034/196] mm: avoid wrapping vm_pgoff in mremap() Date: Mon, 12 Mar 2012 20:12:42 -0400 Message-Id: <1331597724-31358-35-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.9.3 In-Reply-To: <1331597724-31358-1-git-send-email-paul.gortmaker@windriver.com> References: <1331597724-31358-1-git-send-email-paul.gortmaker@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Linus Torvalds ------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. ------------------- commit 982134ba62618c2d69fbbbd166d0a11ee3b7e3d8 upstream. The normal mmap paths all avoid creating a mapping where the pgoff inside the mapping could wrap around due to overflow. However, an expanding mremap() can take such a non-wrapping mapping and make it bigger and cause a wrapping condition. Noticed by Robert Swiecki when running a system call fuzzer, where it caused a BUG_ON() due to terminally confusing the vma_prio_tree code. A vma dumping patch by Hugh then pinpointed the crazy wrapped case. Reported-and-tested-by: Robert Swiecki Acked-by: Hugh Dickins Signed-off-by: Linus Torvalds Signed-off-by: Paul Gortmaker --- mm/mremap.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index 10d5f62..97de5ae 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -274,9 +274,16 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, if (old_len > vma->vm_end - addr) goto Efault; - if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { - if (new_len > old_len) + /* Need to be careful about a growing mapping */ + if (new_len > old_len) { + unsigned long pgoff; + + if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) goto Efault; + pgoff = (addr - vma->vm_start) >> PAGE_SHIFT; + pgoff += vma->vm_pgoff; + if (pgoff + (new_len >> PAGE_SHIFT) < pgoff) + goto Einval; } if (vma->vm_flags & VM_LOCKED) { -- 1.7.9.3