From: Michael Mueller <mimu@xxxxxxxxxxxxxxxxxx> There is a chance to delete not yet delivered I/O interrupts if an exploiter uses the subsystem identification word 0x0000 while processing a KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl. -EINVAL will be returned now instead in that case. Classic interrupts will always have bit 0x10000 set in the schid while adapter interrupts have a zero schid. The clear_io_irq interface is only useful for classic interrupts (as adapter interrupts belong to many devices). Let's make this interface more strict and forbid a schid of 0. Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxxxxxxx> Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx> Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> --- Documentation/virtual/kvm/devices/s390_flic.txt | 3 +++ arch/s390/kvm/interrupt.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt index 2f1cbf1..27ad53c 100644 --- a/Documentation/virtual/kvm/devices/s390_flic.txt +++ b/Documentation/virtual/kvm/devices/s390_flic.txt @@ -156,3 +156,6 @@ FLIC with an unknown group or attribute gives the error code EINVAL (instead of ENXIO, as specified in the API documentation). It is not possible to conclude that a FLIC operation is unavailable based on the error code resulting from a usage attempt. + +Note: The KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl will return EINVAL in case a zero +schid is specified. diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index a3da4f3..c8aacce 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -2191,6 +2191,8 @@ static int clear_io_irq(struct kvm *kvm, struct kvm_device_attr *attr) return -EINVAL; if (copy_from_user(&schid, (void __user *) attr->addr, sizeof(schid))) return -EFAULT; + if (!schid) + return -EINVAL; kfree(kvm_s390_get_io_int(kvm, isc_mask, schid)); /* * If userspace is conforming to the architecture, we can have at most -- 2.9.4
