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From:   Eric Auger <eric.auger@redhat.com>
To:     eric.auger.pro@gmail.com, eric.auger@redhat.com,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com,
        cdall@kernel.org, peter.maydell@linaro.org
Cc:     andre.przywara@arm.com, drjones@redhat.com, wei@redhat.com
Subject: [RFC 01/12] KVM: arm/arm64: Avoid multiple dist->spis kfree
Date:   Mon, 19 Mar 2018 10:20:09 +0100
Message-Id: <1521451220-27754-2-git-send-email-eric.auger@redhat.com>
In-Reply-To: <1521451220-27754-1-git-send-email-eric.auger@redhat.com>
References: <1521451220-27754-1-git-send-email-eric.auger@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

in case kvm_vgic_map_resources() fails, typically if the vgic
distributor is not defined, __kvm_vgic_destroy will be called
several times. Indeed kvm_vgic_map_resources() is called on
first vcpu run. As a result dist->spis is freeed twice and on
the second time it causes a "kernel BUG at mm/slub.c:3912!"

This patch avoids freeing dist->spis twice.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
 virt/kvm/arm/vgic/vgic-init.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 743ca5c..38fd5f1 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -324,7 +324,10 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
 	dist->ready = false;
 	dist->initialized = false;
 
-	kfree(dist->spis);
+	if (dist->spis) {
+		kfree(dist->spis);
+		dist->spis = NULL;
+	}
 	dist->nr_spis = 0;
 
 	if (vgic_supports_direct_msis(kvm))
-- 
2.5.5