[PATCH] KVM: arm64: vgic: Hold config_lock while tearing down a CPU interface

[Marc Zyngier]

Tearing down a vcpu CPU interface involves freeing the private interrupt
array. If we don't hold the lock, we may race against another thread
trying to configure it. Yeah, fuzzers do wonderful things...

Taking the lock early solves this particular problem.

Fixes: 03b3d00a70b5 ("KVM: arm64: vgic: Allocate private interrupts on demand")
Reported-by: Alexander Potapenko <glider at google.com>
Tested-by: Alexander Potapenko <glider at google.com>
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/vgic/vgic-init.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 7f68cf58b978..41feb858ff9a 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -438,14 +438,13 @@ void kvm_vgic_destroy(struct kvm *kvm)
 	unsigned long i;
 
 	mutex_lock(&kvm->slots_lock);
+	mutex_lock(&kvm->arch.config_lock);
 
 	vgic_debug_destroy(kvm);
 
 	kvm_for_each_vcpu(i, vcpu, kvm)
 		__kvm_vgic_vcpu_destroy(vcpu);
 
-	mutex_lock(&kvm->arch.config_lock);
-
 	kvm_vgic_dist_destroy(kvm);
 
 	mutex_unlock(&kvm->arch.config_lock);
-- 
2.39.2