| Message ID | alpine.DEB.2.20.1612111826310.18281@nanos |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Thomas Gleixner <tglx@linutronix.de> Date: Sun, 11 Dec 2016 18:31:22 +0100 (CET) > 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> Applied, thanks Thomas.
--- a/drivers/net/ethernet/3com/3c515.c +++ b/drivers/net/ethernet/3com/3c515.c @@ -628,6 +628,8 @@ static int corkscrew_setup(struct net_de 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++) { @@ -708,6 +710,7 @@ static int corkscrew_open(struct net_dev { int ioaddr = dev->base_addr; struct corkscrew_private *vp = netdev_priv(dev); + bool armtimer = false; __u32 config; int i; @@ -732,12 +735,7 @@ static int corkscrew_open(struct net_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; @@ -777,6 +775,9 @@ static int corkscrew_open(struct net_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", @@ -1427,7 +1428,7 @@ static int corkscrew_close(struct net_de 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);
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 --- drivers/net/ethernet/3com/3c515.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)