Re: [PATCH] scsi: elx: efct: Prevent potential integer overflow in efct_efclib_config()

[Jeff Johnson <quic_jjohnson@quicinc.com>]

On 10/19/2024 2:16 PM, Gax-c wrote:
> From: Zichen Xie <zichenxie0106@gmail.com>
> 
> This was found by a static analyzer.
> There may be a potential integer overflow issue in
> efct_efclib_config(). efc->max_xfer_size is defined
> as "efc->max_xfer_size" while sli->sge_supported_length

I think you wanted to say: as "u64" while...

> and sli_get_max_sgl(&efct->hw.sli) are all "u32".
> The result of the calculation will be limited to
> "u32" without correct casting.
> We recommend adding an extra cast to prevent
> potential integer overflow.

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
Describe your changes in imperative mood, e.g. “make xyzzy do frotz” instead
of “[This patch] makes xyzzy do frotz” or “[I] changed xyzzy to do frotz”, as
if you are giving orders to the codebase to change its behaviour.

So suggest something like:
Cast an operand to u64 to prevent potential u32 overflow.


> 
> Fixes: 4df84e846624 ("scsi: elx: efct: Driver initialization routines")
> Signed-off-by: Zichen Xie <zichenxie0106@gmail.com>
> ---
>  drivers/scsi/elx/efct/efct_driver.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/elx/efct/efct_driver.c b/drivers/scsi/elx/efct/efct_driver.c
> index 55d2301bfd7d..7fe180037c2d 100644
> --- a/drivers/scsi/elx/efct/efct_driver.c
> +++ b/drivers/scsi/elx/efct/efct_driver.c
> @@ -109,7 +109,7 @@ efct_efclib_config(struct efct *efct, struct libefc_function_template *tt)
>  	efc->log_level = EFC_LOG_LIB;
>  
>  	sli = &efct->hw.sli;
> -	efc->max_xfer_size = sli->sge_supported_length *
> +	efc->max_xfer_size = (u64)sli->sge_supported_length *
>  			     sli_get_max_sgl(&efct->hw.sli);
>  	efc->sli = sli;
>  	efc->fcfi = efct->hw.fcf_indicator;