On 03/02/16 16:56, Andre Przywara wrote: > Commit 4b4b4512da2a ("arm/arm64: KVM: Rework the arch timer to use > level-triggered semantics") brought the virtual architected timer > closer to the VGIC. There is one occasion were we don't properly > check for the VGIC actually having been initialized before, but > instead go on to check the active state of some IRQ number. > If userland hasn't instantiated a virtual GIC, we end up with a > kernel NULL pointer dereference: > ========= > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > pgd = ffffffc9745c5000 > [00000000] *pgd=00000009f631e003, *pud=00000009f631e003, *pmd=0000000000000000 > Internal error: Oops: 96000006 [#2] PREEMPT SMP > Modules linked in: > CPU: 0 PID: 2144 Comm: kvm_simplest-ar Tainted: G D 4.5.0-rc2+ #1300 > Hardware name: ARM Juno development board (r1) (DT) > task: ffffffc976da8000 ti: ffffffc976e28000 task.ti: ffffffc976e28000 > PC is at vgic_bitmap_get_irq_val+0x78/0x90 > LR is at kvm_vgic_map_is_active+0xac/0xc8 > pc : [<ffffffc0000b7e28>] lr : [<ffffffc0000b972c>] pstate: 20000145 > .... > ========= > > Fix this by bailing out early of kvm_timer_flush_hwstate() if we don't > have a VGIC at all. > > Reported-by: Cosmin Gorgovan <cosmin@xxxxxxxxxxxxxx> > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # 4.4.x Nice catch, thanks. Acked-by: Marc Zyngier <marc.zyngier@xxxxxxx> M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html