From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60544 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730012AbeIMSyC (ORCPT ); Thu, 13 Sep 2018 14:54:02 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, Eric Van Hensbergen , Ron Minnich , Latchesar Ionkov Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tomas Bortoli , syzbot+735d926e9d1317c3310c@syzkaller.appspotmail.com, Yiwen Jiang , "David S. Miller" , Dominique Martinet , Sasha Levin Subject: [PATCH 4.14 050/115] net/9p/trans_fd.c: fix race by holding the lock Date: Thu, 13 Sep 2018 15:31:10 +0200 Message-Id: <20180913131826.746777224@linuxfoundation.org> In-Reply-To: <20180913131823.327472833@linuxfoundation.org> References: <20180913131823.327472833@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tomas Bortoli [ Upstream commit 9f476d7c540cb57556d3cc7e78704e6cd5100f5f ] It may be possible to run p9_fd_cancel() with a deleted req->req_list and incur in a double del. To fix hold the client->lock while changing the status, so the other threads will be synchronized. Link: http://lkml.kernel.org/r/20180723184253.6682-1-tomasbortoli@gmail.com Signed-off-by: Tomas Bortoli Reported-by: syzbot+735d926e9d1317c3310c@syzkaller.appspotmail.com To: Eric Van Hensbergen To: Ron Minnich To: Latchesar Ionkov Cc: Yiwen Jiang Cc: David S. Miller Signed-off-by: Dominique Martinet Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/9p/trans_fd.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -199,15 +199,14 @@ static void p9_mux_poll_stop(struct p9_c static void p9_conn_cancel(struct p9_conn *m, int err) { struct p9_req_t *req, *rtmp; - unsigned long flags; LIST_HEAD(cancel_list); p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err); - spin_lock_irqsave(&m->client->lock, flags); + spin_lock(&m->client->lock); if (m->err) { - spin_unlock_irqrestore(&m->client->lock, flags); + spin_unlock(&m->client->lock); return; } @@ -219,7 +218,6 @@ static void p9_conn_cancel(struct p9_con list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) { list_move(&req->req_list, &cancel_list); } - spin_unlock_irqrestore(&m->client->lock, flags); list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) { p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req); @@ -228,6 +226,7 @@ static void p9_conn_cancel(struct p9_con req->t_err = err; p9_client_cb(m->client, req, REQ_STATUS_ERROR); } + spin_unlock(&m->client->lock); } static int @@ -385,8 +384,9 @@ static void p9_read_work(struct work_str if (m->req->status != REQ_STATUS_ERROR) status = REQ_STATUS_RCVD; list_del(&m->req->req_list); - spin_unlock(&m->client->lock); + /* update req->status while holding client->lock */ p9_client_cb(m->client, m->req, status); + spin_unlock(&m->client->lock); m->rc.sdata = NULL; m->rc.offset = 0; m->rc.capacity = 0;