From patchwork Wed Dec 9 12:41:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: wangyunjian X-Patchwork-Id: 11961265 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2AF3FC4167B for ; Wed, 9 Dec 2020 12:42:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D088323BCB for ; Wed, 9 Dec 2020 12:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731798AbgLIMmq (ORCPT ); Wed, 9 Dec 2020 07:42:46 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:9048 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730929AbgLIMme (ORCPT ); Wed, 9 Dec 2020 07:42:34 -0500 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4Crc9X12VGzhYl3; Wed, 9 Dec 2020 20:41:20 +0800 (CST) Received: from localhost (10.174.243.127) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.487.0; Wed, 9 Dec 2020 20:41:43 +0800 From: wangyunjian To: , CC: , , , , , Yunjian Wang Subject: [PATCH net v2] tun: fix ubuf refcount incorrectly on error path Date: Wed, 9 Dec 2020 20:41:43 +0800 Message-ID: <1607517703-18472-1-git-send-email-wangyunjian@huawei.com> X-Mailer: git-send-email 1.9.5.msysgit.1 In-Reply-To: <1606982459-41752-1-git-send-email-wangyunjian@huawei.com> References: <1606982459-41752-1-git-send-email-wangyunjian@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.243.127] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Yunjian Wang After setting callback for ubuf_info of skb, the callback (vhost_net_zerocopy_callback) will be called to decrease the refcount when freeing skb. But when an exception occurs afterwards, the error handling in vhost handle_tx() will try to decrease the same refcount again. This is wrong and fix this by delay copying ubuf_info until we're sure there's no errors. Fixes: 4477138fa0ae ("tun: properly test for IFF_UP") Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver") Signed-off-by: Yunjian Wang --- v2: Updated code, fix by delay copying ubuf_info --- drivers/net/tun.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 2dc1988a8973..2ea822328e73 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1637,6 +1637,20 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, return NULL; } +/* copy ubuf_info for callback when skb has no error */ +static inline void tun_copy_ubuf_info(struct sk_buff *skb, bool zerocopy, void *msg_control) +{ + if (zerocopy) { + skb_shinfo(skb)->destructor_arg = msg_control; + skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; + skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; + } else if (msg_control) { + struct ubuf_info *uarg = msg_control; + + uarg->callback(uarg, false); + } +} + /* Get packet from user space buffer */ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, void *msg_control, struct iov_iter *from, @@ -1812,16 +1826,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, break; } - /* copy skb_ubuf_info for callback when skb has no error */ - if (zerocopy) { - skb_shinfo(skb)->destructor_arg = msg_control; - skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY; - skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG; - } else if (msg_control) { - struct ubuf_info *uarg = msg_control; - uarg->callback(uarg, false); - } - skb_reset_network_header(skb); skb_probe_transport_header(skb); skb_record_rx_queue(skb, tfile->queue_index); @@ -1830,6 +1834,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, struct bpf_prog *xdp_prog; int ret; + tun_copy_ubuf_info(skb, zerocopy, msg_control); local_bh_disable(); rcu_read_lock(); xdp_prog = rcu_dereference(tun->xdp_prog); @@ -1881,6 +1886,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, return -ENOMEM; } + tun_copy_ubuf_info(skb, zerocopy, msg_control); local_bh_disable(); napi_gro_frags(&tfile->napi); local_bh_enable(); @@ -1889,6 +1895,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, struct sk_buff_head *queue = &tfile->sk.sk_write_queue; int queue_len; + tun_copy_ubuf_info(skb, zerocopy, msg_control); spin_lock_bh(&queue->lock); __skb_queue_tail(queue, skb); queue_len = skb_queue_len(queue); @@ -1899,8 +1906,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, local_bh_enable(); } else if (!IS_ENABLED(CONFIG_4KSTACKS)) { + tun_copy_ubuf_info(skb, zerocopy, msg_control); tun_rx_batched(tun, tfile, skb, more); } else { + tun_copy_ubuf_info(skb, zerocopy, msg_control); netif_rx_ni(skb); } rcu_read_unlock();