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 B4E3CCDB465 for ; Mon, 16 Oct 2023 08:59:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230152AbjJPI7i (ORCPT ); Mon, 16 Oct 2023 04:59:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232564AbjJPI7h (ORCPT ); Mon, 16 Oct 2023 04:59:37 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7778DE8 for ; Mon, 16 Oct 2023 01:59:35 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EC7FC433C7; Mon, 16 Oct 2023 08:59:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697446775; bh=3zNAflOWgZzKRVADdqB/55YvWlB1To9FsOkDONpJCP8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cayQry/4fZG3cpCD5UqMPBAMmJQdKL788AnWai5Qm4Xwhn2BW4eiv19exT8jq+9Vz RTPKpqKqkJWXLPnp+XLVmENKWE2P1f5ud0nZvMAhKPkTKlJkePlBkxYckge7jIkiy6 MDA9IIJ8RG5rS/OOJuSpRXHPp8m17PcUXvkpFtYo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Maxime Jayat , Lukas Magel , Oliver Hartkopp , Marc Kleine-Budde , Sasha Levin Subject: [PATCH 6.1 043/131] can: isotp: isotp_sendmsg(): fix TX state detection and wait behavior Date: Mon, 16 Oct 2023 10:40:26 +0200 Message-ID: <20231016084001.142952122@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231016084000.050926073@linuxfoundation.org> References: <20231016084000.050926073@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lukas Magel [ Upstream commit d9c2ba65e651467de739324d978b04ed8729f483 ] With patch [1], isotp_poll was updated to also queue the poller in the so->wait queue, which is used for send state changes. Since the queue now also contains polling tasks that are not interested in sending, the queue fill state can no longer be used as an indication of send readiness. As a consequence, nonblocking writes can lead to a race and lock-up of the socket if there is a second task polling the socket in parallel. With this patch, isotp_sendmsg does not consult wq_has_sleepers but instead tries to atomically set so->tx.state and waits on so->wait if it is unable to do so. This behavior is in alignment with isotp_poll, which also checks so->tx.state to determine send readiness. V2: - Revert direct exit to goto err_event_drop [1] https://lore.kernel.org/all/20230331125511.372783-1-michal.sojka@cvut.cz Reported-by: Maxime Jayat Closes: https://lore.kernel.org/linux-can/11328958-453f-447f-9af8-3b5824dfb041@munic.io/ Signed-off-by: Lukas Magel Reviewed-by: Oliver Hartkopp Fixes: 79e19fa79cb5 ("can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events") Link: https://github.com/pylessard/python-udsoncan/issues/178#issuecomment-1743786590 Link: https://lore.kernel.org/all/20230827092205.7908-1-lukas.magel@posteo.net Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin --- net/can/isotp.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/net/can/isotp.c b/net/can/isotp.c index 8c97f4061ffd7..545889935d39c 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -925,21 +925,18 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size) if (!so->bound || so->tx.state == ISOTP_SHUTDOWN) return -EADDRNOTAVAIL; -wait_free_buffer: - /* we do not support multiple buffers - for now */ - if (wq_has_sleeper(&so->wait) && (msg->msg_flags & MSG_DONTWAIT)) - return -EAGAIN; + while (cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SENDING) != ISOTP_IDLE) { + /* we do not support multiple buffers - for now */ + if (msg->msg_flags & MSG_DONTWAIT) + return -EAGAIN; - /* wait for complete transmission of current pdu */ - err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE); - if (err) - goto err_event_drop; - - if (cmpxchg(&so->tx.state, ISOTP_IDLE, ISOTP_SENDING) != ISOTP_IDLE) { if (so->tx.state == ISOTP_SHUTDOWN) return -EADDRNOTAVAIL; - goto wait_free_buffer; + /* wait for complete transmission of current pdu */ + err = wait_event_interruptible(so->wait, so->tx.state == ISOTP_IDLE); + if (err) + goto err_event_drop; } if (!size || size > MAX_MSG_LENGTH) { -- 2.40.1