linux-kernel - [PATCH v7 01/13] KVM: arm/arm64: Set dist->spis to NULL after kfree

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Date:   Sun, 20 May 2018 23:22:40 +0200
From:   Eric Auger <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, eric.auger@...hat.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, marc.zyngier@....com,
        christoffer.dall@....com, peter.maydell@...aro.org
Cc:     andre.przywara@....com, drjones@...hat.com, wei@...hat.com
Subject: [PATCH v7 01/13] KVM: arm/arm64: Set dist->spis to NULL after kfree

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 more than once
and on the second time it causes a "kernel BUG at mm/slub.c:3912!"

Set dist->spis to NULL to avoid the crash.

Fixes: ad275b8bb1e6 ("KVM: arm/arm64: vgic-new: vgic_init: implement
vgic_init")

Signed-off-by: Eric Auger <eric.auger@...hat.com>
Reviewed-by: Marc Zyngier <marc.zyngier@....com>
Reviewed-by: Christoffer Dall <christoffer.dall@....com>

---

v2 -> v3:
- added Marc's R-b and Fixed commit
---
 virt/kvm/arm/vgic/vgic-init.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index e07156c..9a5aed7 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -308,6 +308,7 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
 	dist->initialized = false;
 
 	kfree(dist->spis);
+	dist->spis = NULL;
 	dist->nr_spis = 0;
 
 	if (vgic_supports_direct_msis(kvm))
-- 
2.5.5