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![Duoming Zhou](/assets/img/avatar_default.png)
There are session cleanup problems in ax25_release() and ax25_disconnect(). If we setup a session and then disconnect, the disconnected session is still in "LISTENING" state that is shown below. Active AX.25 sockets Dest Source Device State Vr/Vs Send-Q Recv-Q DL9SAU-4 DL9SAU-3 ??? LISTENING 000/000 0 0 DL9SAU-3 DL9SAU-4 ??? LISTENING 000/000 0 0 The first reason is caused by del_timer_sync() in ax25_release(). The timers of ax25 are used for correct session cleanup. If we use ax25_release() to close ax25 sessions and ax25_dev is not null, the del_timer_sync() functions in ax25_release() will execute. As a result, the sessions could not be cleaned up correctly, because the timers have stopped. In order to solve this problem, this patch adds a device_up flag in ax25_dev in order to judge whether the device is up. If there are sessions to be cleaned up, the del_timer_sync() in ax25_release() will not execute. What's more, we add ax25_cb_del() in ax25_kill_by_device(), because the timers have been stopped and there are no functions that could delete ax25_cb if we do not call ax25_release(). Finally, we reorder the position of ax25_list_lock in ax25_cb_del() in order to synchronize among different functions that call ax25_cb_del(). The second reason is caused by improper check in ax25_disconnect(). The incoming ax25 sessions which ax25->sk is null will close heartbeat timer, because the check "if(!ax25->sk || ..)" is satisfied. As a result, the session could not be cleaned up properly. In order to solve this problem, this patch changes the improper check to "if(ax25->sk && ..)" in ax25_disconnect(). What`s more, the ax25_disconnect() may be called twice, which is not necessary. For example, ax25_kill_by_device() calls ax25_disconnect() and sets ax25->state to AX25_STATE_0, but ax25_release() calls ax25_disconnect() again. In order to solve this problem, this patch add a check in ax25_release(). If the flag of ax25->sk equals to SOCK_DEAD, the ax25_disconnect() in ax25_release() should not be executed. Fixes:82e31755e5
("ax25: Fix UAF bugs in ax25 timers") Fixes:8a367e74c0
("ax25: Fix segfault after sock connection timeout") Reported-and-tested-by: Thomas Osterried <thomas@osterried.de> Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Link: https://lore.kernel.org/r/20220530152158.108619-1-duoming@zju.edu.cn Signed-off-by: Paolo Abeni <pabeni@redhat.com>
214 lines
5 KiB
C
214 lines
5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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*
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* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
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*/
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/slab.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/timer.h>
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#include <linux/string.h>
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#include <linux/sockios.h>
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#include <linux/net.h>
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#include <linux/spinlock.h>
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#include <net/ax25.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/if_arp.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/uaccess.h>
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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ax25_dev *ax25_dev_list;
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DEFINE_SPINLOCK(ax25_dev_lock);
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ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
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{
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ax25_dev *ax25_dev, *res = NULL;
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spin_lock_bh(&ax25_dev_lock);
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for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
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if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
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res = ax25_dev;
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ax25_dev_hold(ax25_dev);
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}
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spin_unlock_bh(&ax25_dev_lock);
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return res;
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}
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/*
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* This is called when an interface is brought up. These are
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* reasonable defaults.
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*/
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void ax25_dev_device_up(struct net_device *dev)
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{
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ax25_dev *ax25_dev;
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if ((ax25_dev = kzalloc(sizeof(*ax25_dev), GFP_ATOMIC)) == NULL) {
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printk(KERN_ERR "AX.25: ax25_dev_device_up - out of memory\n");
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return;
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}
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refcount_set(&ax25_dev->refcount, 1);
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dev->ax25_ptr = ax25_dev;
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ax25_dev->dev = dev;
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dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC);
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ax25_dev->forward = NULL;
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ax25_dev->device_up = true;
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ax25_dev->values[AX25_VALUES_IPDEFMODE] = AX25_DEF_IPDEFMODE;
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ax25_dev->values[AX25_VALUES_AXDEFMODE] = AX25_DEF_AXDEFMODE;
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ax25_dev->values[AX25_VALUES_BACKOFF] = AX25_DEF_BACKOFF;
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ax25_dev->values[AX25_VALUES_CONMODE] = AX25_DEF_CONMODE;
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ax25_dev->values[AX25_VALUES_WINDOW] = AX25_DEF_WINDOW;
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ax25_dev->values[AX25_VALUES_EWINDOW] = AX25_DEF_EWINDOW;
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ax25_dev->values[AX25_VALUES_T1] = AX25_DEF_T1;
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ax25_dev->values[AX25_VALUES_T2] = AX25_DEF_T2;
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ax25_dev->values[AX25_VALUES_T3] = AX25_DEF_T3;
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ax25_dev->values[AX25_VALUES_IDLE] = AX25_DEF_IDLE;
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ax25_dev->values[AX25_VALUES_N2] = AX25_DEF_N2;
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ax25_dev->values[AX25_VALUES_PACLEN] = AX25_DEF_PACLEN;
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ax25_dev->values[AX25_VALUES_PROTOCOL] = AX25_DEF_PROTOCOL;
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ax25_dev->values[AX25_VALUES_DS_TIMEOUT]= AX25_DEF_DS_TIMEOUT;
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#if defined(CONFIG_AX25_DAMA_SLAVE) || defined(CONFIG_AX25_DAMA_MASTER)
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ax25_ds_setup_timer(ax25_dev);
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#endif
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spin_lock_bh(&ax25_dev_lock);
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ax25_dev->next = ax25_dev_list;
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ax25_dev_list = ax25_dev;
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spin_unlock_bh(&ax25_dev_lock);
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ax25_dev_hold(ax25_dev);
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ax25_register_dev_sysctl(ax25_dev);
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}
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void ax25_dev_device_down(struct net_device *dev)
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{
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ax25_dev *s, *ax25_dev;
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if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
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return;
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ax25_unregister_dev_sysctl(ax25_dev);
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spin_lock_bh(&ax25_dev_lock);
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#ifdef CONFIG_AX25_DAMA_SLAVE
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ax25_ds_del_timer(ax25_dev);
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#endif
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/*
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* Remove any packet forwarding that points to this device.
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*/
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for (s = ax25_dev_list; s != NULL; s = s->next)
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if (s->forward == dev)
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s->forward = NULL;
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if ((s = ax25_dev_list) == ax25_dev) {
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ax25_dev_list = s->next;
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goto unlock_put;
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}
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while (s != NULL && s->next != NULL) {
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if (s->next == ax25_dev) {
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s->next = ax25_dev->next;
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goto unlock_put;
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}
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s = s->next;
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}
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spin_unlock_bh(&ax25_dev_lock);
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dev->ax25_ptr = NULL;
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ax25_dev_put(ax25_dev);
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return;
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unlock_put:
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spin_unlock_bh(&ax25_dev_lock);
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ax25_dev_put(ax25_dev);
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dev->ax25_ptr = NULL;
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dev_put_track(dev, &ax25_dev->dev_tracker);
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ax25_dev_put(ax25_dev);
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}
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int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd)
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{
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ax25_dev *ax25_dev, *fwd_dev;
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if ((ax25_dev = ax25_addr_ax25dev(&fwd->port_from)) == NULL)
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return -EINVAL;
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switch (cmd) {
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case SIOCAX25ADDFWD:
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fwd_dev = ax25_addr_ax25dev(&fwd->port_to);
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if (!fwd_dev) {
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ax25_dev_put(ax25_dev);
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return -EINVAL;
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}
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if (ax25_dev->forward) {
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ax25_dev_put(fwd_dev);
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ax25_dev_put(ax25_dev);
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return -EINVAL;
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}
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ax25_dev->forward = fwd_dev->dev;
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ax25_dev_put(fwd_dev);
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ax25_dev_put(ax25_dev);
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break;
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case SIOCAX25DELFWD:
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if (!ax25_dev->forward) {
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ax25_dev_put(ax25_dev);
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return -EINVAL;
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}
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ax25_dev->forward = NULL;
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ax25_dev_put(ax25_dev);
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break;
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default:
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ax25_dev_put(ax25_dev);
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return -EINVAL;
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}
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return 0;
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}
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struct net_device *ax25_fwd_dev(struct net_device *dev)
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{
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ax25_dev *ax25_dev;
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if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
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return dev;
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if (ax25_dev->forward == NULL)
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return dev;
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return ax25_dev->forward;
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}
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/*
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* Free all memory associated with device structures.
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*/
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void __exit ax25_dev_free(void)
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{
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ax25_dev *s, *ax25_dev;
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spin_lock_bh(&ax25_dev_lock);
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ax25_dev = ax25_dev_list;
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while (ax25_dev != NULL) {
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s = ax25_dev;
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dev_put_track(ax25_dev->dev, &ax25_dev->dev_tracker);
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ax25_dev = ax25_dev->next;
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kfree(s);
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}
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ax25_dev_list = NULL;
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spin_unlock_bh(&ax25_dev_lock);
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}
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