From patchwork Thu Mar 18 03:42:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Bohac X-Patchwork-Id: 404625 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=-13.8 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 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 D91DAC433E6 for ; Thu, 18 Mar 2021 03:44:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D73664F10 for ; Thu, 18 Mar 2021 03:44:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229598AbhCRDnQ (ORCPT ); Wed, 17 Mar 2021 23:43:16 -0400 Received: from mx2.suse.de ([195.135.220.15]:37116 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbhCRDmz (ORCPT ); Wed, 17 Mar 2021 23:42:55 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DEBD1ACC6; Thu, 18 Mar 2021 03:42:53 +0000 (UTC) Date: Thu, 18 Mar 2021 04:42:53 +0100 From: Jiri Bohac To: "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, Jiri Pirko Subject: [PATCH] net: check all name nodes in __dev_alloc_name Message-ID: <20210318034253.w4w2p3kvi4m6vqp5@dwarf.suse.cz> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org __dev_alloc_name(), when supplied with a name containing '%d', will search for the first available device number to generate a unique device name. Since commit ff92741270bf8b6e78aa885f166b68c7a67ab13a ("net: introduce name_node struct to be used in hashlist") network devices may have alternate names. __dev_alloc_name() does take these alternate names into account, possibly generating a name that is already taken and failing with -ENFILE as a result. This demonstrates the bug: # rmmod dummy 2>/dev/null # ip link property add dev lo altname dummy0 # modprobe dummy numdummies=1 modprobe: ERROR: could not insert 'dummy': Too many open files in system Instead of creating a device named dummy1, modprobe fails. Fix this by checking all the names in the d->name_node list, not just d->name. Signed-off-by: Jiri Bohac Fixes: ff92741270bf ("net: introduce name_node struct to be used in hashlist") diff --git a/net/core/dev.c b/net/core/dev.c index 6c5967e80132..7cbcd8d37e91 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1184,6 +1184,18 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf) return -ENOMEM; for_each_netdev(net, d) { + struct netdev_name_node *name_node; + list_for_each_entry(name_node, &d->name_node->list, list) { + if (!sscanf(name_node->name, name, &i)) + continue; + if (i < 0 || i >= max_netdevices) + continue; + + /* avoid cases where sscanf is not exact inverse of printf */ + snprintf(buf, IFNAMSIZ, name, i); + if (!strncmp(buf, name_node->name, IFNAMSIZ)) + set_bit(i, inuse); + } if (!sscanf(d->name, name, &i)) continue; if (i < 0 || i >= max_netdevices)