Re: [PATCH v7 1/3] fpga: dfl: add bounds check in dfh_get_param_size()

[Greg KH]

On Mon, May 18, 2026 at 10:52:16AM -0600, Sebastian Alba Vives wrote:
> dfh_get_param_size() can return a parameter size larger than the feature
> region because the loop bounds check is evaluated before incrementing
> size. If the EOP (End of Parameters) bit is set in the same iteration,
> the inflated size is returned without re-validation against max.
> 
> This can cause create_feature_instance() to call memcpy_fromio() with a
> size exceeding the ioremap'd region when a malicious FPGA device provides
> crafted DFHv1 parameter headers.
> 
> Add a bounds check after the size increment to ensure the accumulated
> size never exceeds the feature boundary.
> 
> Fixes: 4747ab89b4a6 ("fpga: dfl: add basic support for DFHv1")
> Signed-off-by: Sebastian Alba Vives <sebasjosue84@xxxxxxxxx>
> ---
> Changes in v7:
>   - Correct the Fixes: tag commit hash (checkpatch).
>     Reported by Xu Yilun.
> Changes in v6:
>   - Rebase onto linux-next. Add cover letter.
>     Suggested by Xu Yilun.
> Changes in v5:
>   - Add blank line after the new bounds check.
>     Suggested by Xu Yilun.
> Changes in v2:
>   - Use (size > max) instead of (size + DFHv1_PARAM_HDR > max).
>     Suggested by Xu Yilun.
> ---
>  drivers/fpga/dfl.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 4087a36a0..4c63c7c85 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -1132,6 +1132,8 @@ static int dfh_get_param_size(void __iomem *dfh_base, resource_size_t max)
>  			return -EINVAL;
>  
>  		size += next * sizeof(u64);
> +		if (size > max)
> +			return -EINVAL;
>  
>  		if (FIELD_GET(DFHv1_PARAM_HDR_NEXT_EOP, v))
>  			return size;
> -- 
> 2.43.0
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
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created.  Hopefully you will not take offence and will fix the problem
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