From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A2C8C433FF for ; Fri, 2 Aug 2019 09:53:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D85DA206A2 for ; Fri, 2 Aug 2019 09:53:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739591; bh=wQTbVWD0hWehFQRGaYAw0lN9RAc85xx/ByvIBOS072w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Z2rP3490LpqfzAynf0pKZzA1DRDKeH1WOwZIPt2zZxD48VaBCBa9fSmBRUFRyKkwZ f4AY066Sh8qiOUE/kN+GHnI2ZjXUK+KNtYa6BNsiwS9l5bKouoCWZIy1EQ5rF1arHP lkprilfIpl/7PdOmFEegBiKSJB91DYgijtQnsZug= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406162AbfHBJxK (ORCPT ); Fri, 2 Aug 2019 05:53:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:59070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406136AbfHBJxI (ORCPT ); Fri, 2 Aug 2019 05:53:08 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7F9642064A; Fri, 2 Aug 2019 09:53:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739588; bh=wQTbVWD0hWehFQRGaYAw0lN9RAc85xx/ByvIBOS072w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jD189B9n/v0qLA8sT86VMSfxMuWcBdQW8vWevvz834Ey6WfV9E/UAosDt2SBQ2st8 2ab9qxJqDHuiZ+r+rNXp/CEtoNQWE3JosSP+/+/sk7WxkN8HAFuMqHkyXEvLKAySb5 V85hMY3p3QlINMaYa7aWJ9F0zS4EnD6SvWkCrfEc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , "Peter Zijlstra (Intel)" , Linus Torvalds , Petr Mladek , Sergey Senozhatsky , Thomas Gleixner , Will Deacon , Ingo Molnar Subject: [PATCH 4.9 221/223] sched/fair: Dont free p->numa_faults with concurrent readers Date: Fri, 2 Aug 2019 11:37:26 +0200 Message-Id: <20190802092250.912173369@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092238.692035242@linuxfoundation.org> References: <20190802092238.692035242@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jann Horn commit 16d51a590a8ce3befb1308e0e7ab77f3b661af33 upstream. When going through execve(), zero out the NUMA fault statistics instead of freeing them. During execve, the task is reachable through procfs and the scheduler. A concurrent /proc/*/sched reader can read data from a freed ->numa_faults allocation (confirmed by KASAN) and write it back to userspace. I believe that it would also be possible for a use-after-free read to occur through a race between a NUMA fault and execve(): task_numa_fault() can lead to task_numa_compare(), which invokes task_weight() on the currently running task of a different CPU. Another way to fix this would be to make ->numa_faults RCU-managed or add extra locking, but it seems easier to wipe the NUMA fault statistics on execve. Signed-off-by: Jann Horn Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Petr Mladek Cc: Sergey Senozhatsky Cc: Thomas Gleixner Cc: Will Deacon Fixes: 82727018b0d3 ("sched/numa: Call task_numa_free() from do_execve()") Link: https://lkml.kernel.org/r/20190716152047.14424-1-jannh@google.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- fs/exec.c | 2 +- include/linux/sched.h | 4 ++-- kernel/fork.c | 2 +- kernel/sched/fair.c | 24 ++++++++++++++++++++---- 4 files changed, 24 insertions(+), 8 deletions(-) --- a/fs/exec.c +++ b/fs/exec.c @@ -1790,7 +1790,7 @@ static int do_execveat_common(int fd, st current->fs->in_exec = 0; current->in_execve = 0; acct_update_integrals(current); - task_numa_free(current); + task_numa_free(current, false); free_bprm(bprm); kfree(pathbuf); putname(filename); --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2044,7 +2044,7 @@ static inline bool in_vfork(struct task_ extern void task_numa_fault(int last_node, int node, int pages, int flags); extern pid_t task_numa_group_id(struct task_struct *p); extern void set_numabalancing_state(bool enabled); -extern void task_numa_free(struct task_struct *p); +extern void task_numa_free(struct task_struct *p, bool final); extern bool should_numa_migrate_memory(struct task_struct *p, struct page *page, int src_nid, int dst_cpu); #else @@ -2059,7 +2059,7 @@ static inline pid_t task_numa_group_id(s static inline void set_numabalancing_state(bool enabled) { } -static inline void task_numa_free(struct task_struct *p) +static inline void task_numa_free(struct task_struct *p, bool final) { } static inline bool should_numa_migrate_memory(struct task_struct *p, --- a/kernel/fork.c +++ b/kernel/fork.c @@ -389,7 +389,7 @@ void __put_task_struct(struct task_struc WARN_ON(tsk == current); cgroup_free(tsk); - task_numa_free(tsk); + task_numa_free(tsk, true); security_task_free(tsk); exit_creds(tsk); delayacct_tsk_free(tsk); --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2257,13 +2257,23 @@ no_join: return; } -void task_numa_free(struct task_struct *p) +/* + * Get rid of NUMA staticstics associated with a task (either current or dead). + * If @final is set, the task is dead and has reached refcount zero, so we can + * safely free all relevant data structures. Otherwise, there might be + * concurrent reads from places like load balancing and procfs, and we should + * reset the data back to default state without freeing ->numa_faults. + */ +void task_numa_free(struct task_struct *p, bool final) { struct numa_group *grp = p->numa_group; - void *numa_faults = p->numa_faults; + unsigned long *numa_faults = p->numa_faults; unsigned long flags; int i; + if (!numa_faults) + return; + if (grp) { spin_lock_irqsave(&grp->lock, flags); for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) @@ -2276,8 +2286,14 @@ void task_numa_free(struct task_struct * put_numa_group(grp); } - p->numa_faults = NULL; - kfree(numa_faults); + if (final) { + p->numa_faults = NULL; + kfree(numa_faults); + } else { + p->total_numa_faults = 0; + for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) + numa_faults[i] = 0; + } } /*