diff options
| author | Thomas Huth <thuth@redhat.com> | 2019-09-12 13:54:38 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-21 07:14:05 +0200 |
| commit | 9761a7fed014915072e0085ec37434125fb78c6b (patch) | |
| tree | 6588428c9cbdb2c113b5bfef0f7920ed09774272 | |
| parent | 49a210f8966fd7b265532d4ed80b05b2c1b96e39 (diff) | |
KVM: s390: Do not leak kernel stack data in the KVM_S390_INTERRUPT ioctl
commit 53936b5bf35e140ae27e4bbf0447a61063f400da upstream.
When the userspace program runs the KVM_S390_INTERRUPT ioctl to inject
an interrupt, we convert them from the legacy struct kvm_s390_interrupt
to the new struct kvm_s390_irq via the s390int_to_s390irq() function.
However, this function does not take care of all types of interrupts
that we can inject into the guest later (see do_inject_vcpu()). Since we
do not clear out the s390irq values before calling s390int_to_s390irq(),
there is a chance that we copy random data from the kernel stack which
could be leaked to the userspace later.
Specifically, the problem exists with the KVM_S390_INT_PFAULT_INIT
interrupt: s390int_to_s390irq() does not handle it, and the function
__inject_pfault_init() later copies irq->u.ext which contains the
random kernel stack data. This data can then be leaked either to
the guest memory in __deliver_pfault_init(), or the userspace might
retrieve it directly with the KVM_S390_GET_IRQ_STATE ioctl.
Fix it by handling that interrupt type in s390int_to_s390irq(), too,
and by making sure that the s390irq struct is properly pre-initialized.
And while we're at it, make sure that s390int_to_s390irq() now
directly returns -EINVAL for unknown interrupt types, so that we
immediately get a proper error code in case we add more interrupt
types to do_inject_vcpu() without updating s390int_to_s390irq()
sometime in the future.
Cc: stable@vger.kernel.org
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/kvm/20190912115438.25761-1-thuth@redhat.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/s390/kvm/interrupt.c | 10 | ||||
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 2 |
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c index be4db07f70d3..95126d25aed5 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -1652,6 +1652,16 @@ int s390int_to_s390irq(struct kvm_s390_interrupt *s390int, case KVM_S390_MCHK: irq->u.mchk.mcic = s390int->parm64; break; + case KVM_S390_INT_PFAULT_INIT: + irq->u.ext.ext_params = s390int->parm; + irq->u.ext.ext_params2 = s390int->parm64; + break; + case KVM_S390_RESTART: + case KVM_S390_INT_CLOCK_COMP: + case KVM_S390_INT_CPU_TIMER: + break; + default: + return -EINVAL; } return 0; } diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 07f571900676..ea20b60edde7 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3105,7 +3105,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, } case KVM_S390_INTERRUPT: { struct kvm_s390_interrupt s390int; - struct kvm_s390_irq s390irq; + struct kvm_s390_irq s390irq = {}; r = -EFAULT; if (copy_from_user(&s390int, argp, sizeof(s390int))) |