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KVM: hyperv: idr_find needs RCU protection 

Even though the eventfd is released after the KVM SRCU grace period
elapses, the conn_to_evt data structure itself is not; it uses RCU
internally, instead.  Fix the read-side critical section to happen
under rcu_read_lock/unlock; the result is still protected by
vcpu->kvm->srcu.

Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2018-05-07 19:24:34 +02:00
parent 6356ee0c96
commit 452a68d0ef
1 changed files with 3 additions and 1 deletions
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4
arch/x86/kvm/hyperv.c
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@ -1296,8 +1296,10 @@ static u16 kvm_hvcall_signal_event(struct kvm_vcpu *vcpu, bool fast, u64 param)
if (param & ~KVM_HYPERV_CONN_ID_MASK)
return HV_STATUS_INVALID_HYPERCALL_INPUT;
/* conn_to_evt is protected by vcpu->kvm->srcu */
/* the eventfd is protected by vcpu->kvm->srcu, but conn_to_evt isn't */
rcu_read_lock();
eventfd = idr_find(&vcpu->kvm->arch.hyperv.conn_to_evt, param);
rcu_read_unlock();
if (!eventfd)
return HV_STATUS_INVALID_PORT_ID;