From nobody Fri Dec 19 18:42:54 2025 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 0424EC433FE for ; Sat, 22 Oct 2022 08:27:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233687AbiJVI1u (ORCPT ); Sat, 22 Oct 2022 04:27:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233890AbiJVI1J (ORCPT ); Sat, 22 Oct 2022 04:27:09 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05AA41DEC29; Sat, 22 Oct 2022 01:00:53 -0700 (PDT) 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 15F48B82DF2; Sat, 22 Oct 2022 07:59:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 84365C433D7; Sat, 22 Oct 2022 07:59:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666425554; bh=KM+yqH9LxgCI1cABBreSlmVHgkz04CgVC7Pe9gqdX88=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cj1aLwZ9UDxYwuGd9s+eAqmtu7ZNo4K50CtRSbqqWCJMrZ00w1//ArAYqWXD5x6bo wIlrBFOJ7iboREFQHucEFKXmz7B13I9j32BA9XvnP39X+QngU3stAPCQELYHLS2lAP Yv7a5cRU8Gh8zdgM+fhgPev1VOgZskvJE7yAh0e0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexander Aring , David Teigland , Sasha Levin Subject: [PATCH 5.19 540/717] fs: dlm: fix race in lowcomms Date: Sat, 22 Oct 2022 09:26:59 +0200 Message-Id: <20221022072522.228629924@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221022072415.034382448@linuxfoundation.org> References: <20221022072415.034382448@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Alexander Aring [ Upstream commit 30ea3257e8766027c4d8d609dcbd256ff9a76073 ] This patch fixes a race between queue_work() in _dlm_lowcomms_commit_msg() and srcu_read_unlock(). The queue_work() can take the final reference of a dlm_msg and so msg->idx can contain garbage which is signaled by the following warning: [ 676.237050] ------------[ cut here ]------------ [ 676.237052] WARNING: CPU: 0 PID: 1060 at include/linux/srcu.h:189 dlm_lo= wcomms_commit_msg+0x41/0x50 [ 676.238945] Modules linked in: dlm_locktorture torture rpcsec_gss_krb5 i= ntel_rapl_msr intel_rapl_common iTCO_wdt iTCO_vendor_support qxl kvm_intel = drm_ttm_helper vmw_vsock_virtio_transport kvm vmw_vsock_virtio_transport_co= mmon ttm irqbypass crc32_pclmul joydev crc32c_intel serio_raw drm_kms_helpe= r vsock virtio_scsi virtio_console virtio_balloon snd_pcm drm syscopyarea s= ysfillrect sysimgblt snd_timer fb_sys_fops i2c_i801 lpc_ich snd i2c_smbus s= oundcore pcspkr [ 676.244227] CPU: 0 PID: 1060 Comm: lock_torture_wr Not tainted 5.19.0-rc= 3+ #1546 [ 676.245216] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-2.module+el8= .7.0+15506+033991b0 04/01/2014 [ 676.246460] RIP: 0010:dlm_lowcomms_commit_msg+0x41/0x50 [ 676.247132] Code: fe ff ff ff 75 24 48 c7 c6 bd 0f 49 bb 48 c7 c7 38 7c = 01 bd e8 00 e7 ca ff 89 de 48 c7 c7 60 78 01 bd e8 42 3d cd ff 5b 5d c3 <0f= > 0b eb d8 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 [ 676.249253] RSP: 0018:ffffa401c18ffc68 EFLAGS: 00010282 [ 676.249855] RAX: 0000000000000001 RBX: 00000000ffff8b76 RCX: 00000000000= 00006 [ 676.250713] RDX: 0000000000000000 RSI: ffffffffbccf3a10 RDI: ffffffffbcc= 7b62e [ 676.251610] RBP: ffffa401c18ffc70 R08: 0000000000000001 R09: 00000000000= 00001 [ 676.252481] R10: 0000000000000001 R11: 0000000000000001 R12: 00000000000= 00005 [ 676.253421] R13: ffff8b76786ec370 R14: ffff8b76786ec370 R15: ffff8b76786= ec480 [ 676.254257] FS: 0000000000000000(0000) GS:ffff8b7777800000(0000) knlGS:= 0000000000000000 [ 676.255239] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 676.255897] CR2: 00005590205d88b8 CR3: 000000017656c003 CR4: 00000000007= 70ee0 [ 676.256734] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 00000000000= 00000 [ 676.257567] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 00000000000= 00400 [ 676.258397] PKRU: 55555554 [ 676.258729] Call Trace: [ 676.259063] [ 676.259354] dlm_midcomms_commit_mhandle+0xcc/0x110 [ 676.259964] queue_bast+0x8b/0xb0 [ 676.260423] grant_pending_locks+0x166/0x1b0 [ 676.261007] _unlock_lock+0x75/0x90 [ 676.261469] unlock_lock.isra.57+0x62/0xa0 [ 676.262009] dlm_unlock+0x21e/0x330 [ 676.262457] ? lock_torture_stats+0x80/0x80 [dlm_locktorture] [ 676.263183] torture_unlock+0x5a/0x90 [dlm_locktorture] [ 676.263815] ? preempt_count_sub+0xba/0x100 [ 676.264361] ? complete+0x1d/0x60 [ 676.264777] lock_torture_writer+0xb8/0x150 [dlm_locktorture] [ 676.265555] kthread+0x10a/0x130 [ 676.266007] ? kthread_complete_and_exit+0x20/0x20 [ 676.266616] ret_from_fork+0x22/0x30 [ 676.267097] [ 676.267381] irq event stamp: 9579855 [ 676.267824] hardirqs last enabled at (9579863): [] __= up_console_sem+0x58/0x60 [ 676.268896] hardirqs last disabled at (9579872): [] __= up_console_sem+0x3d/0x60 [ 676.270008] softirqs last enabled at (9579798): [] __= do_softirq+0x349/0x4c7 [ 676.271438] softirqs last disabled at (9579897): [] ir= q_exit_rcu+0xb0/0xf0 [ 676.272796] ---[ end trace 0000000000000000 ]--- I reproduced this warning with dlm_locktorture test which is currently not upstream. However this patch fix the issue by make a additional refcount between dlm_lowcomms_new_msg() and dlm_lowcomms_commit_msg(). In case of the race the kref_put() in dlm_lowcomms_commit_msg() will be the final put. Signed-off-by: Alexander Aring Signed-off-by: David Teigland Signed-off-by: Sasha Levin --- fs/dlm/lowcomms.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c index 19e82f08c0e0..c80ee6a95d17 100644 --- a/fs/dlm/lowcomms.c +++ b/fs/dlm/lowcomms.c @@ -1336,6 +1336,8 @@ struct dlm_msg *dlm_lowcomms_new_msg(int nodeid, int = len, gfp_t allocation, return NULL; } =20 + /* for dlm_lowcomms_commit_msg() */ + kref_get(&msg->ref); /* we assume if successful commit must called */ msg->idx =3D idx; return msg; @@ -1375,6 +1377,8 @@ void dlm_lowcomms_commit_msg(struct dlm_msg *msg) { _dlm_lowcomms_commit_msg(msg); srcu_read_unlock(&connections_srcu, msg->idx); + /* because dlm_lowcomms_new_msg() */ + kref_put(&msg->ref, dlm_msg_release); } #endif =20 --=20 2.35.1