Re: [PATCH v7 15/15] KVM: s390: fix possible null pointer dereference in pending_irqs()

[Pierre Morel]

On 31/01/2019 09:52, Michael Mueller wrote:

Assure a GISA is in use before accessing the IPM to avoid a
null pointer dereference issue.

Signed-off-by: Michael Mueller <m...@linux.ibm.com>
Reported-by: Halil Pasic <pa...@linux.ibm.com>
---
  arch/s390/kvm/interrupt.c | 10 +++++++---
  1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index d322400ca587..660ec87b6e60 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -329,9 +329,13 @@ static inline unsigned long pending_irqs_no_gisa(struct 
kvm_vcpu *vcpu)

static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)

  {
-       return pending_irqs_no_gisa(vcpu) |
-               gisa_get_ipm(vcpu->kvm->arch.gisa_int.origin) <<
-                       IRQ_PEND_IO_ISC_7;
+       struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
+       unsigned long pending_mask;
+
+       pending_mask = pending_irqs_no_gisa(vcpu);
+       if (gi->origin)
+               pending_mask |= gisa_get_ipm(gi->origin) << IRQ_PEND_IO_ISC_7;
+       return pending_mask;
  }

static inline int isc_to_irq_type(unsigned long isc)

Reviewed-by: Pierre Morel<pmo...@linux.ibm.com>


--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany