From nobody Mon Dec 15 17:56:07 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 8FE25FA3740 for ; Mon, 24 Oct 2022 19:24:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233188AbiJXTYA (ORCPT ); Mon, 24 Oct 2022 15:24:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231225AbiJXTWf (ORCPT ); Mon, 24 Oct 2022 15:22:35 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 105563DBE5; Mon, 24 Oct 2022 10:57:29 -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 sin.source.kernel.org (Postfix) with ESMTPS id 0C04BCE1369; Mon, 24 Oct 2022 11:53:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3710C433C1; Mon, 24 Oct 2022 11:53:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666612436; bh=iQieQ4Y/Cp6gHS2C7Lg2w/a+l9Ieo+k4kqJju/g1xY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D7OibFfoBNzu8/fN5abML/2hzCLHjivTdsFSvcXSjFdzqftgqmUTh/jPvFZxdVun/ YJdj71Bm6T7jsYrVZD+moin9frmYE6WfENwA8Q1qm/3Jurtxmnok+oxJfcN2zFcpjr dpixHWEtJWhcYrC7hoZ82Pw0Jy43Mlk1kWpI98bU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+38e6c55d4969a14c1534@syzkaller.appspotmail.com, Shigeru Yoshida , Josef Bacik , Jens Axboe , Sasha Levin Subject: [PATCH 4.14 196/210] nbd: Fix hung when signal interrupts nbd_start_device_ioctl() Date: Mon, 24 Oct 2022 13:31:53 +0200 Message-Id: <20221024113003.321506243@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024112956.797777597@linuxfoundation.org> References: <20221024112956.797777597@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: Shigeru Yoshida [ Upstream commit 1de7c3cf48fc41cd95adb12bd1ea9033a917798a ] syzbot reported hung task [1]. The following program is a simplified version of the reproducer: int main(void) { int sv[2], fd; if (socketpair(AF_UNIX, SOCK_STREAM, 0, sv) < 0) return 1; if ((fd =3D open("/dev/nbd0", 0)) < 0) return 1; if (ioctl(fd, NBD_SET_SIZE_BLOCKS, 0x81) < 0) return 1; if (ioctl(fd, NBD_SET_SOCK, sv[0]) < 0) return 1; if (ioctl(fd, NBD_DO_IT) < 0) return 1; return 0; } When signal interrupt nbd_start_device_ioctl() waiting the condition atomic_read(&config->recv_threads) =3D=3D 0, the task can hung because it waits the completion of the inflight IOs. This patch fixes the issue by clearing queue, not just shutdown, when signal interrupt nbd_start_device_ioctl(). Link: https://syzkaller.appspot.com/bug?id=3D7d89a3ffacd2b83fdd39549bc4d8e0= a89ef21239 [1] Reported-by: syzbot+38e6c55d4969a14c1534@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20220907163502.577561-1-syoshida@redhat.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/nbd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 338d02a67afb..f01b8860ba14 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1258,10 +1258,12 @@ static int nbd_start_device_ioctl(struct nbd_device= *nbd, struct block_device *b mutex_unlock(&nbd->config_lock); ret =3D wait_event_interruptible(config->recv_wq, atomic_read(&config->recv_threads) =3D=3D 0); - if (ret) + if (ret) { sock_shutdown(nbd); - flush_workqueue(nbd->recv_workq); + nbd_clear_que(nbd); + } =20 + flush_workqueue(nbd->recv_workq); mutex_lock(&nbd->config_lock); bd_set_size(bdev, 0); /* user requested, ignore socket errors */ --=20 2.35.1