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![Arvid Brodin](/assets/img/avatar_default.png)
To repeat:
$ sudo ip link del hsr0
BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
IP: [<ffffffff8187f495>] hsr_del_port+0x15/0xa0
etc...
Bug description:
As part of the hsr master device destruction, hsr_del_port() is called for each of
the hsr ports. At each such call, the master device is updated regarding features
and mtu. When the master device is freed before the slave interfaces, master will
be NULL in hsr_del_port(), which led to a NULL pointer dereference.
Additionally, dev_put() was called on the master device itself in hsr_del_port(),
causing a refcnt error.
A third bug in the same code path was that the rtnl lock was not taken before
hsr_del_port() was called as part of hsr_dev_destroy().
The reporter (Nicolas Dichtel) also said: "hsr_netdev_notify() supposes that the
port will always be available when the notification is for an hsr interface. It's
wrong. For example, netdev_wait_allrefs() may resend NETDEV_UNREGISTER.". As a
precaution against this, a check for port == NULL was added in hsr_dev_notify().
Reported-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Fixes: 51f3c60531
("net/hsr: Move slave init to hsr_slave.c.")
Signed-off-by: Arvid Brodin <arvid.brodin@alten.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
200 lines
4.3 KiB
C
200 lines
4.3 KiB
C
/* Copyright 2011-2014 Autronica Fire and Security AS
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* Author(s):
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* 2011-2014 Arvid Brodin, arvid.brodin@alten.se
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*/
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#include "hsr_slave.h"
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#include <linux/etherdevice.h>
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#include <linux/if_arp.h>
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#include "hsr_main.h"
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#include "hsr_device.h"
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#include "hsr_forward.h"
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#include "hsr_framereg.h"
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static rx_handler_result_t hsr_handle_frame(struct sk_buff **pskb)
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{
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struct sk_buff *skb = *pskb;
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struct hsr_port *port;
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if (!skb_mac_header_was_set(skb)) {
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WARN_ONCE(1, "%s: skb invalid", __func__);
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return RX_HANDLER_PASS;
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}
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rcu_read_lock(); /* hsr->node_db, hsr->ports */
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port = hsr_port_get_rcu(skb->dev);
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if (hsr_addr_is_self(port->hsr, eth_hdr(skb)->h_source)) {
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/* Directly kill frames sent by ourselves */
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kfree_skb(skb);
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goto finish_consume;
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}
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if (eth_hdr(skb)->h_proto != htons(ETH_P_PRP))
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goto finish_pass;
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skb_push(skb, ETH_HLEN);
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hsr_forward_skb(skb, port);
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finish_consume:
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rcu_read_unlock(); /* hsr->node_db, hsr->ports */
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return RX_HANDLER_CONSUMED;
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finish_pass:
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rcu_read_unlock(); /* hsr->node_db, hsr->ports */
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return RX_HANDLER_PASS;
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}
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bool hsr_port_exists(const struct net_device *dev)
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{
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return rcu_access_pointer(dev->rx_handler) == hsr_handle_frame;
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}
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static int hsr_check_dev_ok(struct net_device *dev)
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{
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/* Don't allow HSR on non-ethernet like devices */
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if ((dev->flags & IFF_LOOPBACK) || (dev->type != ARPHRD_ETHER) ||
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(dev->addr_len != ETH_ALEN)) {
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netdev_info(dev, "Cannot use loopback or non-ethernet device as HSR slave.\n");
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return -EINVAL;
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}
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/* Don't allow enslaving hsr devices */
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if (is_hsr_master(dev)) {
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netdev_info(dev, "Cannot create trees of HSR devices.\n");
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return -EINVAL;
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}
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if (hsr_port_exists(dev)) {
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netdev_info(dev, "This device is already a HSR slave.\n");
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return -EINVAL;
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}
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if (dev->priv_flags & IFF_802_1Q_VLAN) {
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netdev_info(dev, "HSR on top of VLAN is not yet supported in this driver.\n");
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return -EINVAL;
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}
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if (dev->priv_flags & IFF_DONT_BRIDGE) {
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netdev_info(dev, "This device does not support bridging.\n");
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return -EOPNOTSUPP;
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}
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/* HSR over bonded devices has not been tested, but I'm not sure it
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* won't work...
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*/
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return 0;
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}
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/* Setup device to be added to the HSR bridge. */
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static int hsr_portdev_setup(struct net_device *dev, struct hsr_port *port)
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{
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int res;
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dev_hold(dev);
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res = dev_set_promiscuity(dev, 1);
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if (res)
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goto fail_promiscuity;
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/* FIXME:
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* What does net device "adjacency" mean? Should we do
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* res = netdev_master_upper_dev_link(port->dev, port->hsr->dev); ?
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*/
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res = netdev_rx_handler_register(dev, hsr_handle_frame, port);
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if (res)
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goto fail_rx_handler;
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dev_disable_lro(dev);
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return 0;
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fail_rx_handler:
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dev_set_promiscuity(dev, -1);
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fail_promiscuity:
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dev_put(dev);
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return res;
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}
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int hsr_add_port(struct hsr_priv *hsr, struct net_device *dev,
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enum hsr_port_type type)
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{
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struct hsr_port *port, *master;
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int res;
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if (type != HSR_PT_MASTER) {
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res = hsr_check_dev_ok(dev);
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if (res)
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return res;
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}
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port = hsr_port_get_hsr(hsr, type);
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if (port != NULL)
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return -EBUSY; /* This port already exists */
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port = kzalloc(sizeof(*port), GFP_KERNEL);
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if (port == NULL)
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return -ENOMEM;
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if (type != HSR_PT_MASTER) {
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res = hsr_portdev_setup(dev, port);
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if (res)
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goto fail_dev_setup;
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}
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port->hsr = hsr;
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port->dev = dev;
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port->type = type;
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list_add_tail_rcu(&port->port_list, &hsr->ports);
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synchronize_rcu();
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master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
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netdev_update_features(master->dev);
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dev_set_mtu(master->dev, hsr_get_max_mtu(hsr));
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return 0;
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fail_dev_setup:
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kfree(port);
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return res;
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}
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void hsr_del_port(struct hsr_port *port)
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{
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struct hsr_priv *hsr;
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struct hsr_port *master;
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hsr = port->hsr;
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master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
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list_del_rcu(&port->port_list);
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if (port != master) {
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if (master != NULL) {
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netdev_update_features(master->dev);
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dev_set_mtu(master->dev, hsr_get_max_mtu(hsr));
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}
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netdev_rx_handler_unregister(port->dev);
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dev_set_promiscuity(port->dev, -1);
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}
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/* FIXME?
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* netdev_upper_dev_unlink(port->dev, port->hsr->dev);
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*/
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synchronize_rcu();
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if (port != master)
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dev_put(port->dev);
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}
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