Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753536AbdHKQRi (ORCPT ); Fri, 11 Aug 2017 12:17:38 -0400 Received: from mail-lf0-f65.google.com ([209.85.215.65]:36950 "EHLO mail-lf0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753504AbdHKQRh (ORCPT ); Fri, 11 Aug 2017 12:17:37 -0400 From: Alexander Popov To: Kees Cook , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Paul E McKenney , Ingo Molnar , Tejun Heo , Andy Lutomirski , Nicolas Pitre , linux-mm@kvack.org, Rik van Riel , Tycho Andersen , Alexander Popov , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [linux-next][PATCH v2] mm/slub.c: add a naive detection of double free or corruption Date: Fri, 11 Aug 2017 19:17:26 +0300 Message-Id: <1502468246-1262-1-git-send-email-alex.popov@linux.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 867 Lines: 27 Add an assertion similar to "fasttop" check in GNU C Library allocator as a part of SLAB_FREELIST_HARDENED feature. An object added to a singly linked freelist should not point to itself. That helps to detect some double free errors (e.g. CVE-2017-2636) without slub_debug and KASAN. Signed-off-by: Alexander Popov --- mm/slub.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/slub.c b/mm/slub.c index b9c7f1a..77b2781 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -290,6 +290,10 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) { unsigned long freeptr_addr = (unsigned long)object + s->offset; +#ifdef CONFIG_SLAB_FREELIST_HARDENED + BUG_ON(object == fp); /* naive detection of double free or corruption */ +#endif + *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr); } -- 2.7.4