[PATCH] iommu/vt-d: fix race between free_irte() and get_irte()

Greg Edwards
2014-07-22T14:32:40Z

get_irte() can race with free_irte() and dereference a NULL iommu
pointer.

Signed-off-by: Greg Edwards <gedwards@ddn.com>
Cc: stable@vger.kernel.org
---
drivers/iommu/intel_irq_remapping.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 9b17489..2d67e6d 100644
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -70,6 +70,12 @@ static int get_irte(int irq, struct irte *entry)

raw_spin_lock_irqsave(&irq_2_ir_lock, flags);

+ /* ensure we're not racing with free_irte() */
+ if (unlikely(!irq_iommu->iommu)) {
+ raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
+ return -1;
+ }
+
index = irq_iommu->irte_index + irq_iommu->sub_handle;
*entry = *(irq_iommu->iommu->ir_table->base + index);

--
1.9.3