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

[Mark Gross <mgross@linux.intel.com>]

On Tue, Oct 23, 2007 at 10:57:51AM +0200, Takashi Iwai wrote:
> Fix possible array overflow:
> 
> drivers/pci/intel-iommu.c: In function ‘dmar_get_fault_reason’:
> drivers/pci/intel-iommu.c:753: warning: array subscript is above array bounds
> drivers/pci/intel-iommu.c: In function ‘iommu_page_fault’:
> drivers/pci/intel-iommu.c:753: warning: array subscript is above array bounds
> 
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> 
> ---
>  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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