Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758750Ab1DZVN4 (ORCPT ); Tue, 26 Apr 2011 17:13:56 -0400 Received: from mga14.intel.com ([143.182.124.37]:19974 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758698Ab1DZVNt (ORCPT ); Tue, 26 Apr 2011 17:13:49 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.64,270,1301900400"; d="scan'208";a="425950930" From: Andi Kleen References: <20110426212.641772347@firstfloor.org> In-Reply-To: <20110426212.641772347@firstfloor.org> To: torvalds@linux-foundation.org, hughd@google.com, gregkh@suse.de, ak@linux.intel.com, linux-kernel@vger.kernel.org, stable@kernel.org, tim.bird@am.sony.com Subject: [PATCH] [21/106] mm: avoid wrapping vm_pgoff in mremap() Message-Id: <20110426211259.D4DF63E1886@tassilo.jf.intel.com> Date: Tue, 26 Apr 2011 14:12:59 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1979 Lines: 54 2.6.35-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Linus Torvalds 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: Greg Kroah-Hartman Signed-off-by: Andi Kleen --- mm/mremap.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) Index: linux-2.6.35.y/mm/mremap.c =================================================================== --- linux-2.6.35.y.orig/mm/mremap.c +++ linux-2.6.35.y/mm/mremap.c @@ -274,9 +274,16 @@ static struct vm_area_struct *vma_to_res 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) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/