From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:48158 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728429AbeJSCA3 (ORCPT ); Thu, 18 Oct 2018 22:00:29 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sven Eckelmann , Marek Lindner , Simon Wunderlich , Sasha Levin Subject: [PATCH 4.18 07/53] batman-adv: Fix segfault when writing to throughput_override Date: Thu, 18 Oct 2018 19:54:00 +0200 Message-Id: <20181018175417.981931621@linuxfoundation.org> In-Reply-To: <20181018175416.561567978@linuxfoundation.org> References: <20181018175416.561567978@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: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Eckelmann [ Upstream commit b9fd14c20871e6189f635e49b32d7789e430b3c8 ] The per hardif sysfs file "batman_adv/throughput_override" prints the resulting change as info text when the users writes to this file. It uses the helper function batadv_info to add it at the same time to the kernel ring buffer and to the batman-adv debug log (when CONFIG_BATMAN_ADV_DEBUG is enabled). The function batadv_info requires as first parameter the batman-adv softif net_device. This parameter is then used to find the private buffer which contains the debug log for this batman-adv interface. But batadv_store_throughput_override used as first argument the slave net_device. This slave device doesn't have the batadv_priv private data which is access by batadv_info. Writing to this file with CONFIG_BATMAN_ADV_DEBUG enabled can either lead to a segfault or to memory corruption. Fixes: 0b5ecc6811bd ("batman-adv: add throughput override attribute to hard_ifaces") Signed-off-by: Sven Eckelmann Acked-by: Marek Lindner Signed-off-by: Simon Wunderlich Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/sysfs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/net/batman-adv/sysfs.c +++ b/net/batman-adv/sysfs.c @@ -1090,8 +1090,9 @@ static ssize_t batadv_store_throughput_o if (old_tp_override == tp_override) goto out; - batadv_info(net_dev, "%s: Changing from: %u.%u MBit to: %u.%u MBit\n", - "throughput_override", + batadv_info(hard_iface->soft_iface, + "%s: %s: Changing from: %u.%u MBit to: %u.%u MBit\n", + "throughput_override", net_dev->name, old_tp_override / 10, old_tp_override % 10, tp_override / 10, tp_override % 10);