From patchwork Wed Dec 23 21:23:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antoine Tenart X-Patchwork-Id: 351765 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 EF6FBC433DB for ; Wed, 23 Dec 2020 21:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4ADD2246B for ; Wed, 23 Dec 2020 21:24:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729186AbgLWVYJ (ORCPT ); Wed, 23 Dec 2020 16:24:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:50970 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729094AbgLWVYJ (ORCPT ); Wed, 23 Dec 2020 16:24:09 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 675A32246B; Wed, 23 Dec 2020 21:23:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1608758609; bh=Qv7BNaQBGigmchrOczr/Unmy93zZ29j4XMAjksBoIWc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=am+ogcDW/UnuyA2x0N8ww9ObN6VNHgWVd9xGlkEEPzkmbXrHpsXxF7rTvRzkx2mUn J89ULD70k68nyRACwA2XVerrEWVDTmXu91UOPPecKMoySKSh1wiQytQR77S/IOTPET 3eq6acPbrBPG6j9+3fWIyrl1uBrao7amCpXJKUk59QCcg3OPLBkkpk0l4KLC+gJRdd V3lDuQSBkCtz1sQ15K8fOE9tb/a1Qn7Lrly58r/ZY+yMQ7Rus7es/eOTCI4p5Zj+wU 59vFUx88vvVNuB97b09csQ0jMKrxgAvh35+FR+rJVSspQNF9feH//i0Hu9HcEncvAL pZkLv02J2AX3Q== From: Antoine Tenart To: davem@davemloft.net, kuba@kernel.org, alexander.duyck@gmail.com Cc: Antoine Tenart , netdev@vger.kernel.org, pabeni@redhat.com Subject: [PATCH net v3 1/4] net-sysfs: take the rtnl lock when storing xps_cpus Date: Wed, 23 Dec 2020 22:23:20 +0100 Message-Id: <20201223212323.3603139-2-atenart@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201223212323.3603139-1-atenart@kernel.org> References: <20201223212323.3603139-1-atenart@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Two race conditions can be triggered when storing xps cpus, resulting in various oops and invalid memory accesses: 1. Calling netdev_set_num_tc while netif_set_xps_queue: - netif_set_xps_queue uses dev->tc_num as one of the parameters to compute the size of new_dev_maps when allocating it. dev->tc_num is also used to access the map, and the compiler may generate code to retrieve this field multiple times in the function. - netdev_set_num_tc sets dev->tc_num. If new_dev_maps is allocated using dev->tc_num and then dev->tc_num is set to a higher value through netdev_set_num_tc, later accesses to new_dev_maps in netif_set_xps_queue could lead to accessing memory outside of new_dev_maps; triggering an oops. 2. Calling netif_set_xps_queue while netdev_set_num_tc is running: 2.1. netdev_set_num_tc starts by resetting the xps queues, dev->tc_num isn't updated yet. 2.2. netif_set_xps_queue is called, setting up the map with the *old* dev->num_tc. 2.3. netdev_set_num_tc updates dev->tc_num. 2.4. Later accesses to the map lead to out of bound accesses and oops. A similar issue can be found with netdev_reset_tc. One way of triggering this is to set an iface up (for which the driver uses netdev_set_num_tc in the open path, such as bnx2x) and writing to xps_cpus in a concurrent thread. With the right timing an oops is triggered. Both issues have the same fix: netif_set_xps_queue, netdev_set_num_tc and netdev_reset_tc should be mutually exclusive. We do that by taking the rtnl lock in xps_cpus_store. Fixes: 184c449f91fe ("net: Add support for XPS with QoS via traffic classes") Signed-off-by: Antoine Tenart --- net/core/net-sysfs.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 999b70c59761..7cc15dec1717 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1396,7 +1396,13 @@ static ssize_t xps_cpus_store(struct netdev_queue *queue, return err; } + if (!rtnl_trylock()) { + free_cpumask_var(mask); + return restart_syscall(); + } + err = netif_set_xps_queue(dev, mask, index); + rtnl_unlock(); free_cpumask_var(mask); From patchwork Wed Dec 23 21:23:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antoine Tenart X-Patchwork-Id: 352235 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 8958CC433E6 for ; Wed, 23 Dec 2020 21:24:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DF132246B for ; Wed, 23 Dec 2020 21:24:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729198AbgLWVYM (ORCPT ); Wed, 23 Dec 2020 16:24:12 -0500 Received: from mail.kernel.org ([198.145.29.99]:50998 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727147AbgLWVYM (ORCPT ); Wed, 23 Dec 2020 16:24:12 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5FFAD22473; Wed, 23 Dec 2020 21:23:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1608758612; bh=7cSPm7QGIHghZ6g3wS5iD5HhlF4JxgKP24qbxWRjUCo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AdeajCkP3NgAQzomHf/14ssHAJDvnS69dT9PeM6hf062YqNgb/zt9aUcycN4kuDU0 1U5KZtlu3+qmjzXMi7hPZ6ih3D5i94xLXt9ZD4AQQkoxUlVdgo/xaUEpSTYU1EhlWz HmCFGu7ZK09xFFwPyR90xJkPDI9CYhqRF+Tg5kvdNoMkHzExMNWOMn2u82eipVwxqH +VV+Pc6UtXGklQgk9tFbcYSTMJAXILf/rjeUm0PWZIFPD0R+atbOJipVK4ow59hqL8 4VvA0+gtELjytFOHMVY3paW2C7/Z/K6oBA6vTlMA0nNuKkBsvK1UXqbCOUWwWSylv5 kEVi9ArwegECg== From: Antoine Tenart To: davem@davemloft.net, kuba@kernel.org, alexander.duyck@gmail.com Cc: Antoine Tenart , netdev@vger.kernel.org, pabeni@redhat.com Subject: [PATCH net v3 2/4] net-sysfs: take the rtnl lock when accessing xps_cpus_map and num_tc Date: Wed, 23 Dec 2020 22:23:21 +0100 Message-Id: <20201223212323.3603139-3-atenart@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201223212323.3603139-1-atenart@kernel.org> References: <20201223212323.3603139-1-atenart@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Accesses to dev->xps_cpus_map (when using dev->num_tc) should be protected by the rtnl lock, like we do for netif_set_xps_queue. I didn't see an actual bug being triggered, but let's be safe here and take the rtnl lock while accessing the map in sysfs. Fixes: 184c449f91fe ("net: Add support for XPS with QoS via traffic classes") Signed-off-by: Antoine Tenart --- net/core/net-sysfs.c | 29 ++++++++++++++++++++++------- 1 file changed, 22 insertions(+), 7 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 7cc15dec1717..65886bfbf822 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1317,8 +1317,8 @@ static const struct attribute_group dql_group = { static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf) { + int cpu, len, ret, num_tc = 1, tc = 0; struct net_device *dev = queue->dev; - int cpu, len, num_tc = 1, tc = 0; struct xps_dev_maps *dev_maps; cpumask_var_t mask; unsigned long index; @@ -1328,22 +1328,31 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue, index = get_netdev_queue_index(queue); + if (!rtnl_trylock()) + return restart_syscall(); + if (dev->num_tc) { /* Do not allow XPS on subordinate device directly */ num_tc = dev->num_tc; - if (num_tc < 0) - return -EINVAL; + if (num_tc < 0) { + ret = -EINVAL; + goto err_rtnl_unlock; + } /* If queue belongs to subordinate dev use its map */ dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev; tc = netdev_txq_to_tc(dev, index); - if (tc < 0) - return -EINVAL; + if (tc < 0) { + ret = -EINVAL; + goto err_rtnl_unlock; + } } - if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) - return -ENOMEM; + if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) { + ret = -ENOMEM; + goto err_rtnl_unlock; + } rcu_read_lock(); dev_maps = rcu_dereference(dev->xps_cpus_map); @@ -1366,9 +1375,15 @@ static ssize_t xps_cpus_show(struct netdev_queue *queue, } rcu_read_unlock(); + rtnl_unlock(); + len = snprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask)); free_cpumask_var(mask); return len < PAGE_SIZE ? len : -EINVAL; + +err_rtnl_unlock: + rtnl_unlock(); + return ret; } static ssize_t xps_cpus_store(struct netdev_queue *queue, From patchwork Wed Dec 23 21:23:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antoine Tenart X-Patchwork-Id: 351764 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 884F2C433DB for ; Wed, 23 Dec 2020 21:24:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 587B52246B for ; Wed, 23 Dec 2020 21:24:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729225AbgLWVYP (ORCPT ); Wed, 23 Dec 2020 16:24:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:51024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727147AbgLWVYP (ORCPT ); Wed, 23 Dec 2020 16:24:15 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3FB362247F; Wed, 23 Dec 2020 21:23:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1608758614; bh=4cMhlCykl7mfzg2nMm1XjPf1LqbO9W6RHroB+SznBiQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kWe8lgTgC6Ug0zei6ck0C9KYcPeouvHNF7d8/lFVx61Bs+T7t9KAfJFT3t7CsjMLi g0Wi66hEXcY4G4v5z9Flq53tWKy/9LKjixPe7AQlKPzv6WeDwRqPvGVNFbiU2jkbls O+m6YVRnCcD9Oh9WGcQmqAe12/fK8xXxW9VfpDrqKMzBGgysDmtYZ9npGT/9OLfrfN oPLW+b7JZKZQB1H1hTMglnsRePkiBLI6orf0mJHz40CjD+yo1NNa5AHdGbVuBtsza/ rsbKcFODVNO12JnY3Dnt54/2ZWogfOv5/OsitctAHsFkGE44K6WRGSPtoPvMl2EVeP dCBzVWnsH4jXw== From: Antoine Tenart To: davem@davemloft.net, kuba@kernel.org, alexander.duyck@gmail.com Cc: Antoine Tenart , netdev@vger.kernel.org, pabeni@redhat.com Subject: [PATCH net v3 3/4] net-sysfs: take the rtnl lock when storing xps_rxqs Date: Wed, 23 Dec 2020 22:23:22 +0100 Message-Id: <20201223212323.3603139-4-atenart@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201223212323.3603139-1-atenart@kernel.org> References: <20201223212323.3603139-1-atenart@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Two race conditions can be triggered when storing xps rxqs, resulting in various oops and invalid memory accesses: 1. Calling netdev_set_num_tc while netif_set_xps_queue: - netif_set_xps_queue uses dev->tc_num as one of the parameters to compute the size of new_dev_maps when allocating it. dev->tc_num is also used to access the map, and the compiler may generate code to retrieve this field multiple times in the function. - netdev_set_num_tc sets dev->tc_num. If new_dev_maps is allocated using dev->tc_num and then dev->tc_num is set to a higher value through netdev_set_num_tc, later accesses to new_dev_maps in netif_set_xps_queue could lead to accessing memory outside of new_dev_maps; triggering an oops. 2. Calling netif_set_xps_queue while netdev_set_num_tc is running: 2.1. netdev_set_num_tc starts by resetting the xps queues, dev->tc_num isn't updated yet. 2.2. netif_set_xps_queue is called, setting up the map with the *old* dev->num_tc. 2.3. netdev_set_num_tc updates dev->tc_num. 2.4. Later accesses to the map lead to out of bound accesses and oops. A similar issue can be found with netdev_reset_tc. One way of triggering this is to set an iface up (for which the driver uses netdev_set_num_tc in the open path, such as bnx2x) and writing to xps_rxqs in a concurrent thread. With the right timing an oops is triggered. Both issues have the same fix: netif_set_xps_queue, netdev_set_num_tc and netdev_reset_tc should be mutually exclusive. We do that by taking the rtnl lock in xps_rxqs_store. Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue") Signed-off-by: Antoine Tenart --- net/core/net-sysfs.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 65886bfbf822..62ca2f2c0ee6 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1499,10 +1499,17 @@ static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf, return err; } + if (!rtnl_trylock()) { + bitmap_free(mask); + return restart_syscall(); + } + cpus_read_lock(); err = __netif_set_xps_queue(dev, mask, index, true); cpus_read_unlock(); + rtnl_unlock(); + bitmap_free(mask); return err ? : len; } From patchwork Wed Dec 23 21:23:23 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Antoine Tenart X-Patchwork-Id: 352234 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 4C33CC433E0 for ; Wed, 23 Dec 2020 21:24:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FDBD2246B for ; Wed, 23 Dec 2020 21:24:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729243AbgLWVYS (ORCPT ); Wed, 23 Dec 2020 16:24:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:51050 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729228AbgLWVYS (ORCPT ); Wed, 23 Dec 2020 16:24:18 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 05E3D224B1; Wed, 23 Dec 2020 21:23:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1608758617; bh=Wdrg+jwVO0FO5FqBU61dcu5tztCz+oq+TGHKbkJ1DvE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=t/WNylpaJKqBR4XKehAoIv0FYmAlrM7UwfWtj/9d5Vn/TlEXDTGRUpm/9WAk48oZO IVlxspHN1Tw9/Co1CHfEDKMhE5C+dHYcYrkYGRcdcf0m+KTnkl+bxorLKYfebrC+cD xUWQ0CqX0umC+fuwZTtSsDcrzgJyrhiFKdtCIfsySwAs7n1gxQ49UYwclG4ue00V+Z +LlKUsXmgi6eBwWXErZVlFSti2/VO/v8lgXFc3esw2R0dPJwN5fJRlmL0a5hn8pjo0 IKcdlSnXEVdoYMqrWG8HM1spBEy6x1+ia6ctxDplZOpXdf1RRArL+E2INM4O1jDCZL d/KGwV7D/LO7w== From: Antoine Tenart To: davem@davemloft.net, kuba@kernel.org, alexander.duyck@gmail.com Cc: Antoine Tenart , netdev@vger.kernel.org, pabeni@redhat.com Subject: [PATCH net v3 4/4] net-sysfs: take the rtnl lock when accessing xps_rxqs_map and num_tc Date: Wed, 23 Dec 2020 22:23:23 +0100 Message-Id: <20201223212323.3603139-5-atenart@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201223212323.3603139-1-atenart@kernel.org> References: <20201223212323.3603139-1-atenart@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Accesses to dev->xps_rxqs_map (when using dev->num_tc) should be protected by the rtnl lock, like we do for netif_set_xps_queue. I didn't see an actual bug being triggered, but let's be safe here and take the rtnl lock while accessing the map in sysfs. Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue") Signed-off-by: Antoine Tenart --- net/core/net-sysfs.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 62ca2f2c0ee6..daf502c13d6d 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -1429,22 +1429,29 @@ static struct netdev_queue_attribute xps_cpus_attribute __ro_after_init static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf) { + int j, len, ret, num_tc = 1, tc = 0; struct net_device *dev = queue->dev; struct xps_dev_maps *dev_maps; unsigned long *mask, index; - int j, len, num_tc = 1, tc = 0; index = get_netdev_queue_index(queue); + if (!rtnl_trylock()) + return restart_syscall(); + if (dev->num_tc) { num_tc = dev->num_tc; tc = netdev_txq_to_tc(dev, index); - if (tc < 0) - return -EINVAL; + if (tc < 0) { + ret = -EINVAL; + goto err_rtnl_unlock; + } } mask = bitmap_zalloc(dev->num_rx_queues, GFP_KERNEL); - if (!mask) - return -ENOMEM; + if (!mask) { + ret = -ENOMEM; + goto err_rtnl_unlock; + } rcu_read_lock(); dev_maps = rcu_dereference(dev->xps_rxqs_map); @@ -1470,10 +1477,16 @@ static ssize_t xps_rxqs_show(struct netdev_queue *queue, char *buf) out_no_maps: rcu_read_unlock(); + rtnl_unlock(); + len = bitmap_print_to_pagebuf(false, buf, mask, dev->num_rx_queues); bitmap_free(mask); return len < PAGE_SIZE ? len : -EINVAL; + +err_rtnl_unlock: + rtnl_unlock(); + return ret; } static ssize_t xps_rxqs_store(struct netdev_queue *queue, const char *buf,