Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758150AbeAIU4z (ORCPT + 1 other); Tue, 9 Jan 2018 15:56:55 -0500 Received: from mail-pf0-f196.google.com ([209.85.192.196]:46186 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757900AbeAIU4u (ORCPT ); Tue, 9 Jan 2018 15:56:50 -0500 X-Google-Smtp-Source: ACJfBot0OCGQAcZOElJBnu5zQ/R+A+NJuWqBxNwEJFM59ANDt3On2MGysKntzACAkI0ifCRW1drEFA== From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Linus Torvalds , David Windsor , Alexander Viro , Andrew Morton , Andy Lutomirski , Christoph Hellwig , Christoph Lameter , "David S. Miller" , Laura Abbott , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christian Borntraeger , Christoffer Dall , Dave Kleikamp , Jan Kara , Luis de Bethencourt , Marc Zyngier , Rik van Riel , Matthew Garrett , linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com Subject: [PATCH 03/36] lkdtm/usercopy: Adjust test to include an offset to check reporting Date: Tue, 9 Jan 2018 12:55:32 -0800 Message-Id: <1515531365-37423-4-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515531365-37423-1-git-send-email-keescook@chromium.org> References: <1515531365-37423-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Instead of doubling the size, push the start position up by 16 bytes to still trigger an overflow. This allows to verify that offset reporting is working correctly. Signed-off-by: Kees Cook --- drivers/misc/lkdtm_usercopy.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/misc/lkdtm_usercopy.c b/drivers/misc/lkdtm_usercopy.c index a64372cc148d..9ebbb031e5e3 100644 --- a/drivers/misc/lkdtm_usercopy.c +++ b/drivers/misc/lkdtm_usercopy.c @@ -119,6 +119,8 @@ static void do_usercopy_heap_size(bool to_user) { unsigned long user_addr; unsigned char *one, *two; + void __user *test_user_addr; + void *test_kern_addr; size_t size = unconst + 1024; one = kmalloc(size, GFP_KERNEL); @@ -139,27 +141,30 @@ static void do_usercopy_heap_size(bool to_user) memset(one, 'A', size); memset(two, 'B', size); + test_user_addr = (void __user *)(user_addr + 16); + test_kern_addr = one + 16; + if (to_user) { pr_info("attempting good copy_to_user of correct size\n"); - if (copy_to_user((void __user *)user_addr, one, size)) { + if (copy_to_user(test_user_addr, test_kern_addr, size / 2)) { pr_warn("copy_to_user failed unexpectedly?!\n"); goto free_user; } pr_info("attempting bad copy_to_user of too large size\n"); - if (copy_to_user((void __user *)user_addr, one, 2 * size)) { + if (copy_to_user(test_user_addr, test_kern_addr, size)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; } } else { pr_info("attempting good copy_from_user of correct size\n"); - if (copy_from_user(one, (void __user *)user_addr, size)) { + if (copy_from_user(test_kern_addr, test_user_addr, size / 2)) { pr_warn("copy_from_user failed unexpectedly?!\n"); goto free_user; } pr_info("attempting bad copy_from_user of too large size\n"); - if (copy_from_user(one, (void __user *)user_addr, 2 * size)) { + if (copy_from_user(test_kern_addr, test_user_addr, size)) { pr_warn("copy_from_user failed, but lacked Oops\n"); goto free_user; } -- 2.7.4