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authorChristoffer Dall <christoffer.dall@linaro.org>2016-08-02 22:05:42 +0200
committerChristoffer Dall <christoffer.dall@linaro.org>2016-08-10 11:41:54 +0200
commit2cccbb368a2bf27d98cf36bb424fbbf5572c0fab (patch)
tree83edb3161029df208d04341330a381b8c6e9f5a1
parent99e5e886a0a59df267ff6838f763b789847df982 (diff)
downloadlinux-stericsson-2cccbb368a2bf27d98cf36bb424fbbf5572c0fab.tar.gz
KVM: arm64: vgic-its: Plug race in vgic_put_irq
Right now the following sequence of events can happen: 1. Thread X calls vgic_put_irq 2. Thread Y calls vgic_add_lpi 3. Thread Y gets lpi_list_lock 4. Thread X drops the ref count to 0 and blocks on lpi_list_lock 5. Thread Y finds the irq via the lpi_list_lock, raises the ref count to 1, and release the lpi_list_lock. 6. Thread X proceeds and frees the irq. Avoid this by holding the spinlock around the kref_put. Reviewed-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
-rw-r--r--virt/kvm/arm/vgic/vgic.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index e7aeac719e09..e83b7fe4baae 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -117,17 +117,17 @@ static void vgic_irq_release(struct kref *ref)
void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
{
- struct vgic_dist *dist;
+ struct vgic_dist *dist = &kvm->arch.vgic;
if (irq->intid < VGIC_MIN_LPI)
return;
- if (!kref_put(&irq->refcount, vgic_irq_release))
+ spin_lock(&dist->lpi_list_lock);
+ if (!kref_put(&irq->refcount, vgic_irq_release)) {
+ spin_unlock(&dist->lpi_list_lock);
return;
+ };
- dist = &kvm->arch.vgic;
-
- spin_lock(&dist->lpi_list_lock);
list_del(&irq->lpi_list);
dist->lpi_list_count--;
spin_unlock(&dist->lpi_list_lock);