Commit e28ceeb1 authored Dec 11, 2016 by Thomas Gleixner Committed by David S. Miller Dec 16, 2016

net/3com/3c515: Fix timer handling, prevent leaks and crashes



The timer handling in this driver is broken in several ways:

- corkscrew_open() initializes and arms a timer before requesting the
  device interrupt. If the request fails the timer stays armed.

  A second call to corkscrew_open will unconditionally reinitialize the
  quued timer and arm it again. Also a immediate device removal will leave
  the timer queued because close() is not called (open() failed) and
  therefore nothing issues del_timer().

  The reinitialization corrupts the link chain in the timer wheel hash
  bucket and causes a NULL pointer dereference when the timer wheel tries
  to operate on that hash bucket. Immediate device removal lets the link
  chain poke into freed and possibly reused memory.

  Solution: Arm the timer after the successful irq request.

- corkscrew_close() uses del_timer()

  On close the timer is disarmed with del_timer() which lets the following
  code race against a concurrent timer expiry function.

  Solution: Use del_timer_sync() instead

- corkscrew_close() calls del_timer() unconditionally

  del_timer() is invoked even if the timer was never initialized. This
  works by chance because the struct containing the timer is zeroed at
  allocation time.

  Solution: Move the setup of the timer into corkscrew_setup().

Reported-by: Matthew Whitehead <tedheadster@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 3e1ed981

drivers/net/ethernet/3com/3c515.c

+8 −7

Original line number	Diff line number	Diff line
		@@ -627,6 +627,8 @@ static int corkscrew_setup(struct net_device *dev, int ioaddr,

		spin_lock_init(&vp->lock);

		setup_timer(&vp->timer, corkscrew_timer, (unsigned long) dev);

		/* Read the station address from the EEPROM. */
		EL3WINDOW(0);
		for (i = 0; i < 0x18; i++) {
		@@ -707,6 +709,7 @@ static int corkscrew_open(struct net_device *dev)
		{
		int ioaddr = dev->base_addr;
		struct corkscrew_private *vp = netdev_priv(dev);
		bool armtimer = false;
		__u32 config;
		int i;

		@@ -731,12 +734,7 @@ static int corkscrew_open(struct net_device *dev)
		if (corkscrew_debug > 1)
		pr_debug("%s: Initial media type %s.\n",
		dev->name, media_tbl[dev->if_port].name);

		init_timer(&vp->timer);
		vp->timer.expires = jiffies + media_tbl[dev->if_port].wait;
		vp->timer.data = (unsigned long) dev;
		vp->timer.function = corkscrew_timer; /* timer handler */
		add_timer(&vp->timer);
		armtimer = true;
		} else
		dev->if_port = vp->default_media;

		@@ -776,6 +774,9 @@ static int corkscrew_open(struct net_device *dev)
		return -EAGAIN;
		}

		if (armtimer)
		mod_timer(&vp->timer, jiffies + media_tbl[dev->if_port].wait);

		if (corkscrew_debug > 1) {
		EL3WINDOW(4);
		pr_debug("%s: corkscrew_open() irq %d media status %4.4x.\n",
		@@ -1426,7 +1427,7 @@ static int corkscrew_close(struct net_device *dev)
		dev->name, rx_nocopy, rx_copy, queued_packet);
		}

		del_timer(&vp->timer);
		del_timer_sync(&vp->timer);

		/* Turn off statistics ASAP. We update lp->stats below. */
		outw(StatsDisable, ioaddr + EL3_CMD);