Re: [PATCH] intel-iommu: Fix array overflow

From: Mark Gross
Date: Wed Oct 24 2007 - 19:34:28 EST


On Tue, Oct 23, 2007 at 10:57:51AM +0200, Takashi Iwai wrote:
> Fix possible array overflow:
>
> drivers/pci/intel-iommu.c: In function âdmar_get_fault_reasonâ:
> drivers/pci/intel-iommu.c:753: warning: array subscript is above array bounds
> drivers/pci/intel-iommu.c: In function âiommu_page_faultâ:
> drivers/pci/intel-iommu.c:753: warning: array subscript is above array bounds
>
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
>
> ---
> drivers/pci/intel-iommu.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
> index b3d7031..e4b0a0d 100644
> --- a/drivers/pci/intel-iommu.c
> +++ b/drivers/pci/intel-iommu.c
> @@ -749,8 +749,8 @@ static char *fault_reason_strings[] =
>
> char *dmar_get_fault_reason(u8 fault_reason)
> {
> - if (fault_reason > MAX_FAULT_REASON_IDX)
> - return fault_reason_strings[MAX_FAULT_REASON_IDX];
> + if (fault_reason >= MAX_FAULT_REASON_IDX)
> + return fault_reason_strings[MAX_FAULT_REASON_IDX - 1];

This looks like what the code meant to implement. I guess future
hardware may be able to generate more types of faults, otherwise I'd put
a BUG here.

--mgross


> else
> return fault_reason_strings[fault_reason];
> }
> -
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