BugLink: http://bugs.launchpad.net/bugs/1694621

commit 2c4569ca

 upstream.

irq_set_chained_handler_and_data() sets up the chained interrupt and then
stores the handler data.

That's racy against an immediate interrupt which gets handled before the
store of the handler data happened. The handler will dereference a NULL
pointer and crash.

Cure it by storing handler data before installing the chained handler.

Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>