![Cong Wang](/assets/img/avatar_default.png)
There are multiple issues here: 1. After freeing dev->ax25_ptr, we need to set it to NULL otherwise we may use a dangling pointer. 2. There is a race between ax25_setsockopt() and device notifier as reported by syzbot. Close it by holding RTNL lock. 3. We need to test if dev->ax25_ptr is NULL before using it. Reported-and-tested-by: syzbot+ae6bb869cbed29b29040@syzkaller.appspotmail.com Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
201 lines
4.7 KiB
C
201 lines
4.7 KiB
C
/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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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, (ax25_address *)ax25_dev->dev->dev_addr) == 0) {
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res = 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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dev->ax25_ptr = ax25_dev;
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ax25_dev->dev = dev;
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dev_hold(dev);
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ax25_dev->forward = NULL;
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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_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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spin_unlock_bh(&ax25_dev_lock);
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dev->ax25_ptr = NULL;
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dev_put(dev);
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kfree(ax25_dev);
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return;
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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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spin_unlock_bh(&ax25_dev_lock);
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dev->ax25_ptr = NULL;
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dev_put(dev);
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kfree(ax25_dev);
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return;
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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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}
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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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if ((fwd_dev = ax25_addr_ax25dev(&fwd->port_to)) == NULL)
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return -EINVAL;
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if (ax25_dev->forward != NULL)
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return -EINVAL;
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ax25_dev->forward = fwd_dev->dev;
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break;
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case SIOCAX25DELFWD:
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if (ax25_dev->forward == NULL)
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return -EINVAL;
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ax25_dev->forward = NULL;
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break;
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default:
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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(ax25_dev->dev);
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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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