linux-kernel - [PATCH] pci/dmar: correct off-by-one error

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Date:	Wed, 19 Aug 2009 15:26:11 -0600
From:	Troy Heber <troy.heber@...com>
To:	David Woodhouse <dwmw2@...radead.org>,
	iommu@...ts.linux-foundation.org
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] pci/dmar: correct off-by-one error

pci/dmar: correct off-by-one error in dmar_fault()
    
DMAR faults are recorded into a ring of "fault recording registers".
fault_index is a 0-based index into the ring. The code allows the
0-based fault_index to be equal to the total number of fault registers
available from the cap_num_fault_regs() macro, which causes access
beyond the last available register. 
    
Signed-off-by Troy Heber <troy.heber@...com>

---
 drivers/pci/dmar.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index 7b287cb..c0c776f 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -1212,7 +1212,7 @@ irqreturn_t dmar_fault(int irq, void *dev_id)
 				source_id, guest_addr);
 
 		fault_index++;
-		if (fault_index > cap_num_fault_regs(iommu->cap))
+		if (fault_index >= cap_num_fault_regs(iommu->cap))
 			fault_index = 0;
 		spin_lock_irqsave(&iommu->register_lock, flag);
 	}
--
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