From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932705AbdJJSIk (ORCPT ); Tue, 10 Oct 2017 14:08:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53436 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932593AbdJJSFJ (ORCPT ); Tue, 10 Oct 2017 14:05:09 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 312F8883CF Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=joe.lawrence@redhat.com From: Joe Lawrence To: linux-kernel@vger.kernel.org Cc: Mikulas Patocka , Michael Kerrisk , Randy Dunlap Subject: [PATCH v3 4/4] sysctl: check for UINT_MAX before unsigned int min/max Date: Tue, 10 Oct 2017 14:04:49 -0400 Message-Id: <1507658689-11669-5-git-send-email-joe.lawrence@redhat.com> In-Reply-To: <1507658689-11669-1-git-send-email-joe.lawrence@redhat.com> References: <1507658689-11669-1-git-send-email-joe.lawrence@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Tue, 10 Oct 2017 18:05:09 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mikulas noticed in the existing do_proc_douintvec_minmax_conv() and do_proc_dopipe_max_size_conv() introduced in this patchset, that they inconsistently handle overflow and min/max range inputs: For example: 0 ... param->min - 1 ---> ERANGE param->min ... param->max ---> the value is accepted param->max + 1 ... 0x100000000L + param->min - 1 ---> ERANGE 0x100000000L + param->min ... 0x100000000L + param->max ---> EINVAL 0x100000000L + param->max + 1, 0x200000000L + param->min - 1 ---> ERANGE 0x200000000L + param->min ... 0x200000000L + param->max ---> EINVAL 0x200000000L + param->max + 1, 0x300000000L + param->min - 1 ---> ERANGE In do_proc_do*() routines which store values into unsigned int variables (4 bytes wide for 64-bit builds), first validate that the input unsigned long value (8 bytes wide for 64-bit builds) will fit inside the smaller unsigned int variable. Then check that the unsigned int value falls inside the specified parameter min, max range. Otherwise the unsigned long -> unsigned int conversion drops leading bits from the input value, leading to the inconsistent pattern Mikulas documented above. Reported-by: Mikulas Patocka Signed-off-by: Joe Lawrence --- kernel/sysctl.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 30b01b22014d..a04907158c90 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -2587,12 +2587,13 @@ static int do_proc_douintvec_minmax_conv(unsigned long *lvalp, if (write) { unsigned int val = *lvalp; + if (*lvalp > UINT_MAX) + return -EINVAL; + if ((param->min && *param->min > val) || (param->max && *param->max < val)) return -ERANGE; - if (*lvalp > UINT_MAX) - return -EINVAL; *valp = val; } else { unsigned int val = *valp; @@ -2643,17 +2644,18 @@ static int do_proc_dopipe_max_size_conv(unsigned long *lvalp, struct do_proc_dopipe_max_size_conv_param *param = data; if (write) { - unsigned int val = round_pipe_size(*lvalp); + unsigned int val; + if (*lvalp > UINT_MAX) + return -EINVAL; + + val = round_pipe_size(*lvalp); if (val == 0) return -EINVAL; if (param->min && *param->min > val) return -ERANGE; - if (*lvalp > UINT_MAX) - return -EINVAL; - *valp = val; } else { unsigned int val = *valp; -- 1.8.3.1