From mboxrd@z Thu Jan 1 00:00:00 1970 From: Serhey Popovych Subject: [PATCH net-next] dev: Correctly get length of alias string in dev_set_alias() Date: Mon, 18 Dec 2017 23:38:35 +0200 Message-ID: <1513633115-16940-1-git-send-email-serhe.popovych@gmail.com> To: netdev@vger.kernel.org Return-path: Received: from mail-lf0-f65.google.com ([209.85.215.65]:44617 "EHLO mail-lf0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936995AbdLRVim (ORCPT ); Mon, 18 Dec 2017 16:38:42 -0500 Received: by mail-lf0-f65.google.com with SMTP id x204so19363010lfa.11 for ; Mon, 18 Dec 2017 13:38:41 -0800 (PST) Received: from tuxracer.localdomain ([2a01:6d80::195:20:96:53]) by smtp.gmail.com with ESMTPSA id z64sm2950516lfa.34.2017.12.18.13.38.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Dec 2017 13:38:39 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: We supply number of bytes available in @alias via @len parameter to dev_set_alias() which is not the same as zero terminated string length that can be shorter. Both dev_set_alias() users (rtnetlink and sysfs) can submit number of bytes up to IFALIASZ with actual string length slightly shorter by putting '\0' not at @len - 1. Use strnlen() to get length of zero terminated string and not access beyond @len. Correct comment about @len and explain how to unset alias (i.e. use zero for @len). Signed-off-by: Serhey Popovych --- net/core/dev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index b0eee49..d362fe6 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1243,7 +1243,7 @@ int dev_change_name(struct net_device *dev, const char *newname) * dev_set_alias - change ifalias of a device * @dev: device * @alias: name up to IFALIASZ - * @len: limit of bytes to copy from info + * @len: number of bytes available in @alias, zero to unset current alias * * Set ifalias for a device, */ @@ -1255,6 +1255,8 @@ int dev_set_alias(struct net_device *dev, const char *alias, size_t len) return -EINVAL; if (len) { + len = strnlen(alias, len); + new_alias = kmalloc(sizeof(*new_alias) + len + 1, GFP_KERNEL); if (!new_alias) return -ENOMEM; -- 1.8.3.1