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| author | Thomas Huth <thuth@redhat.com> | 2019-09-12 14:54:38 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-19 10:08:04 +0300 |
| commit | fd1b7efe8e04ef259e7beb2f68af8d4f7a7e9d8e (patch) | |
| tree | 10c4b9554a7190bf75f77c7b2df4c85b28911a68 /arch/s390 | |
| parent | 3426b361703541faf8223b79f2a3dee553d6bb9f (diff) | |
| download | linux-fd1b7efe8e04ef259e7beb2f68af8d4f7a7e9d8e.tar.xz | |
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>
Diffstat (limited to 'arch/s390')
| -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 5185be314661..28f3796d23c8 100644 --- a/arch/s390/kvm/interrupt.c +++ b/arch/s390/kvm/interrupt.c @@ -1701,6 +1701,16 @@ 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 70a446ec347d..a27fb640adbe 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -3730,7 +3730,7 @@ 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))) |