Re: [Intel-wired-lan] [PATCH] net/i40e: Replace 0-length array with flexible array

[Gustavo A. R. Silva]

On Thu, Jan 05, 2023 at 03:46:01PM -0800, Kees Cook wrote:
> Zero-length arrays are deprecated[1]. Replace struct i40e_lump_tracking's
> "list" 0-length array with a flexible array. Detected with GCC 13,
> using -fstrict-flex-arrays=3:
> 
> In function 'i40e_put_lump',
>     inlined from 'i40e_clear_interrupt_scheme' at drivers/net/ethernet/intel/i40e/i40e_main.c:5145:2:
> drivers/net/ethernet/intel/i40e/i40e_main.c:278:27: warning: array subscript <unknown> is outside array bounds of 'u16[0]' {aka 'short unsigned int[]'} [-Warray-bounds=]
>   278 |                 pile->list[i] = 0;
>       |                 ~~~~~~~~~~^~~
> drivers/net/ethernet/intel/i40e/i40e.h: In function 'i40e_clear_interrupt_scheme':
> drivers/net/ethernet/intel/i40e/i40e.h:179:13: note: while referencing 'list'
>   179 |         u16 list[0];
>       |             ^~~~
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays
> 
> Cc: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>
> Cc: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
> Cc: Paolo Abeni <pabeni@xxxxxxxxxx>
> Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
> Cc: intel-wired-lan@xxxxxxxxxxxxxxxx
> Cc: netdev@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>

Thanks!
--
Gustavo

> ---
>  drivers/net/ethernet/intel/i40e/i40e.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
> index 60e351665c70..3a1c28ca5bb4 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e.h
> @@ -176,7 +176,7 @@ enum i40e_interrupt_policy {
>  
>  struct i40e_lump_tracking {
>  	u16 num_entries;
> -	u16 list[0];
> +	u16 list[];
>  #define I40E_PILE_VALID_BIT  0x8000
>  #define I40E_IWARP_IRQ_PILE_ID  (I40E_PILE_VALID_BIT - 2)
>  };
> -- 
> 2.34.1
> 
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