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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 457B4C636CC for ; Mon, 20 Feb 2023 13:52:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232478AbjBTNwf (ORCPT ); Mon, 20 Feb 2023 08:52:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232476AbjBTNwe (ORCPT ); Mon, 20 Feb 2023 08:52:34 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6C871E5F7 for ; Mon, 20 Feb 2023 05:52:32 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 60ECDB80B96 for ; Mon, 20 Feb 2023 13:52:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC3F1C433D2; Mon, 20 Feb 2023 13:52:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1676901150; bh=g7fWfpQj6/KYdjBeQk3B9bQBV3tkGRiSTU6qM7Y8vio=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o2LgRvZzx68lMdcas390Nks28HgzkdSM9WM9wLbyDBtyVtZoGMmmAKiXhJ+VsZ1hd Qfuy+u/lbFOdCMnWi+UEgnmSbC8KfDd3zG1/U5Ynj39pOJc1sWpcMN7rZlyCNN1/9p owS5GYh6g0Uqsy/7eESD1I3q3C24yZXPW1/ZGJD4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Munehisa Kamata , Mengchi Cheng , Ingo Molnar , Suren Baghdasaryan , Peter Zijlstra Subject: [PATCH 5.15 48/83] sched/psi: Fix use-after-free in ep_remove_wait_queue() Date: Mon, 20 Feb 2023 14:36:21 +0100 Message-Id: <20230220133555.348503007@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230220133553.669025851@linuxfoundation.org> References: <20230220133553.669025851@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Munehisa Kamata commit c2dbe32d5db5c4ead121cf86dabd5ab691fb47fe upstream. If a non-root cgroup gets removed when there is a thread that registered trigger and is polling on a pressure file within the cgroup, the polling waitqueue gets freed in the following path: do_rmdir cgroup_rmdir kernfs_drain_open_files cgroup_file_release cgroup_pressure_release psi_trigger_destroy However, the polling thread still has a reference to the pressure file and will access the freed waitqueue when the file is closed or upon exit: fput ep_eventpoll_release ep_free ep_remove_wait_queue remove_wait_queue This results in use-after-free as pasted below. The fundamental problem here is that cgroup_file_release() (and consequently waitqueue's lifetime) is not tied to the file's real lifetime. Using wake_up_pollfree() here might be less than ideal, but it is in line with the comment at commit 42288cb44c4b ("wait: add wake_up_pollfree()") since the waitqueue's lifetime is not tied to file's one and can be considered as another special case. While this would be fixable by somehow making cgroup_file_release() be tied to the fput(), it would require sizable refactoring at cgroups or higher layer which might be more justifiable if we identify more cases like this. BUG: KASAN: use-after-free in _raw_spin_lock_irqsave+0x60/0xc0 Write of size 4 at addr ffff88810e625328 by task a.out/4404 CPU: 19 PID: 4404 Comm: a.out Not tainted 6.2.0-rc6 #38 Hardware name: Amazon EC2 c5a.8xlarge/, BIOS 1.0 10/16/2017 Call Trace: dump_stack_lvl+0x73/0xa0 print_report+0x16c/0x4e0 kasan_report+0xc3/0xf0 kasan_check_range+0x2d2/0x310 _raw_spin_lock_irqsave+0x60/0xc0 remove_wait_queue+0x1a/0xa0 ep_free+0x12c/0x170 ep_eventpoll_release+0x26/0x30 __fput+0x202/0x400 task_work_run+0x11d/0x170 do_exit+0x495/0x1130 do_group_exit+0x100/0x100 get_signal+0xd67/0xde0 arch_do_signal_or_restart+0x2a/0x2b0 exit_to_user_mode_prepare+0x94/0x100 syscall_exit_to_user_mode+0x20/0x40 do_syscall_64+0x52/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Allocated by task 4404: kasan_set_track+0x3d/0x60 __kasan_kmalloc+0x85/0x90 psi_trigger_create+0x113/0x3e0 pressure_write+0x146/0x2e0 cgroup_file_write+0x11c/0x250 kernfs_fop_write_iter+0x186/0x220 vfs_write+0x3d8/0x5c0 ksys_write+0x90/0x110 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 4407: kasan_set_track+0x3d/0x60 kasan_save_free_info+0x27/0x40 ____kasan_slab_free+0x11d/0x170 slab_free_freelist_hook+0x87/0x150 __kmem_cache_free+0xcb/0x180 psi_trigger_destroy+0x2e8/0x310 cgroup_file_release+0x4f/0xb0 kernfs_drain_open_files+0x165/0x1f0 kernfs_drain+0x162/0x1a0 __kernfs_remove+0x1fb/0x310 kernfs_remove_by_name_ns+0x95/0xe0 cgroup_addrm_files+0x67f/0x700 cgroup_destroy_locked+0x283/0x3c0 cgroup_rmdir+0x29/0x100 kernfs_iop_rmdir+0xd1/0x140 vfs_rmdir+0xfe/0x240 do_rmdir+0x13d/0x280 __x64_sys_rmdir+0x2c/0x30 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: 0e94682b73bf ("psi: introduce psi monitor") Signed-off-by: Munehisa Kamata Signed-off-by: Mengchi Cheng Signed-off-by: Ingo Molnar Acked-by: Suren Baghdasaryan Acked-by: Peter Zijlstra Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/20230106224859.4123476-1-kamatam@amazon.com/ Link: https://lore.kernel.org/r/20230214212705.4058045-1-kamatam@amazon.com Signed-off-by: Greg Kroah-Hartman --- kernel/sched/psi.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -1169,10 +1169,11 @@ void psi_trigger_destroy(struct psi_trig group = t->group; /* - * Wakeup waiters to stop polling. Can happen if cgroup is deleted - * from under a polling process. + * Wakeup waiters to stop polling and clear the queue to prevent it from + * being accessed later. Can happen if cgroup is deleted from under a + * polling process. */ - wake_up_interruptible(&t->event_wait); + wake_up_pollfree(&t->event_wait); mutex_lock(&group->trigger_lock);