From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754944AbeDTNTN (ORCPT ); Fri, 20 Apr 2018 09:19:13 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50200 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754919AbeDTNTL (ORCPT ); Fri, 20 Apr 2018 09:19:11 -0400 Message-Id: <20180420131632.028647632@infradead.org> User-Agent: quilt/0.63-1 Date: Fri, 20 Apr 2018 15:14:14 +0200 From: Peter Zijlstra To: linux-kernel@vger.kernel.org, mingo@kernel.org Cc: tglx@linutronix.de, dan.j.williams@intel.com, torvalds@linux-foundation.org, Dan Carpenter , "Peter Zijlstra" Subject: [PATCH 7/7] sched,autogroup: Fix possible Spectre-v1 for sched_prio_to_weight References: <20180420131407.721875616@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-spectre1-7.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > kernel/sched/autogroup.c:230 proc_sched_autogroup_set_nice() warn: potential spectre issue 'sched_prio_to_weight' Userspace controls @nice, sanitize the array index. Reported-by: Dan Carpenter Signed-off-by: Peter Zijlstra --- kernel/sched/autogroup.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/kernel/sched/autogroup.c +++ b/kernel/sched/autogroup.c @@ -209,7 +209,7 @@ int proc_sched_autogroup_set_nice(struct static unsigned long next = INITIAL_JIFFIES; struct autogroup *ag; unsigned long shares; - int err; + int err, idx; if (nice < MIN_NICE || nice > MAX_NICE) return -EINVAL; @@ -227,7 +227,9 @@ int proc_sched_autogroup_set_nice(struct next = HZ / 10 + jiffies; ag = autogroup_task_get(p); - shares = scale_load(sched_prio_to_weight[nice + 20]); + + idx = array_index_nospec(nice + 20, 40); + shares = scale_load(sched_prio_to_weight[idx]); down_write(&ag->lock); err = sched_group_set_shares(ag->tg, shares);