KVM: PPC: Book3S: Don't crash if irqfd used with no in-kernel XICS emulation
authorPaul Mackerras <paulus@ozlabs.org>
Wed, 10 Aug 2016 01:13:09 +0000 (11:13 +1000)
committerPaul Mackerras <paulus@ozlabs.org>
Fri, 19 Aug 2016 03:00:06 +0000 (13:00 +1000)
commite48ba1cbce12eb4546771d45c09dd94c3404efe8
tree3e4faac42cacb007e71e72cc95e5bb3fc00273ee
parent694d0d0bb2030d2e36df73e2d23d5770511dbc8d
KVM: PPC: Book3S: Don't crash if irqfd used with no in-kernel XICS emulation

It turns out that if userspace creates a pseries-type VM without
in-kernel XICS (interrupt controller) emulation, and then connects
an eventfd to the VM as an irqfd, and the eventfd gets signalled,
that the code will try to deliver an interrupt via the non-existent
XICS object and crash the host kernel with a NULL pointer dereference.

To fix this, we check for the presence of the XICS object before
trying to deliver the interrupt, and return with an error if not.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
arch/powerpc/kvm/book3s_xics.c