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 EEB19FA3741 for ; Mon, 24 Oct 2022 13:04:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235334AbiJXNE3 (ORCPT ); Mon, 24 Oct 2022 09:04:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234954AbiJXNAq (ORCPT ); Mon, 24 Oct 2022 09:00:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A7D31C41D; Mon, 24 Oct 2022 05:19:42 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 841B66128E; Mon, 24 Oct 2022 12:14:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93B46C433D6; Mon, 24 Oct 2022 12:14:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666613684; bh=azAkJqJbnTmmew6QdoYoIdY01RIbkpxXD1N808qO7go=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iQjuipbjFV7GZAhF0XTvuMjgPwvu61qfM76DPBNt/AFVHXNdRrMTnL2QXl41xGRt0 H9QRjUUoSFugl7RV0MmTSJ/BhmsfHZOBgW3Aplq8GfF69t3VI8eKmP/UZua/puDL1v wDkwFzPxbd+gPNziLomUjn20XohORU1AADSEECBk= 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 5.4 231/255] nbd: Fix hung when signal interrupts nbd_start_device_ioctl() Date: Mon, 24 Oct 2022 13:32:21 +0200 Message-Id: <20221024113010.835858082@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024113002.471093005@linuxfoundation.org> References: <20221024113002.471093005@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: linux-kernel@vger.kernel.org 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 = 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) == 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=7d89a3ffacd2b83fdd39549bc4d8e0a89ef21239 [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 09323b0510f0..610dc6a36a9d 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1327,10 +1327,12 @@ static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *b mutex_unlock(&nbd->config_lock); ret = wait_event_interruptible(config->recv_wq, atomic_read(&config->recv_threads) == 0); - if (ret) + if (ret) { sock_shutdown(nbd); - flush_workqueue(nbd->recv_workq); + nbd_clear_que(nbd); + } + flush_workqueue(nbd->recv_workq); mutex_lock(&nbd->config_lock); nbd_bdev_reset(bdev); /* user requested, ignore socket errors */ -- 2.35.1