From: Thomas Gleixner <[email protected]> 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 <[email protected]> > Signed-off-by: Thomas Gleixner <[email protected]> Applied, thanks Thomas.
