RE: [PATCH] RDMA/irdma: avoid fortify-string warning in irdma_clr_wqes

[Saleem, Shiraz]

> Subject: [PATCH] RDMA/irdma: avoid fortify-string warning in irdma_clr_wqes
> 
> From: Arnd Bergmann <arnd@xxxxxxxx>
> 
> Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") triggers a warning for
> fortified memset():
> 
> In function 'fortify_memset_chk',
>     inlined from 'irdma_clr_wqes' at drivers/infiniband/hw/irdma/uk.c:103:4:
> include/linux/fortify-string.h:493:25: error: call to '__write_overflow_field' declared
> with attribute warning: detected write beyond size of field (1st parameter); maybe
> use struct_group()? [-Werror=attribute-warning]
>   493 |                         __write_overflow_field(p_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> The problem here isthat the inner array only has four 8-byte elements, so clearing
> 4096 bytes overflows that. As this structure is part of an outer array, change the
> code to pass a pointer to the irdma_qp_quanta instead, and change the size
> argument for readability, matching the comment above it.
> 
> Fixes: 551c46edc769 ("RDMA/irdma: Add user/kernel shared libraries")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>  drivers/infiniband/hw/irdma/uk.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/irdma/uk.c b/drivers/infiniband/hw/irdma/uk.c
> index 16183e894da7..dd428d915c17 100644
> --- a/drivers/infiniband/hw/irdma/uk.c
> +++ b/drivers/infiniband/hw/irdma/uk.c
> @@ -93,16 +93,18 @@ static int irdma_nop_1(struct irdma_qp_uk *qp)
>   */
>  void irdma_clr_wqes(struct irdma_qp_uk *qp, u32 qp_wqe_idx)  {
> -	__le64 *wqe;
> +	struct irdma_qp_quanta *sq;
>  	u32 wqe_idx;
> 
>  	if (!(qp_wqe_idx & 0x7F)) {
>  		wqe_idx = (qp_wqe_idx + 128) % qp->sq_ring.size;
> -		wqe = qp->sq_base[wqe_idx].elem;
> +		sq = qp->sq_base + wqe_idx;
>  		if (wqe_idx)
> -			memset(wqe, qp->swqe_polarity ? 0 : 0xFF, 0x1000);
> +			memset(sq, qp->swqe_polarity ? 0 : 0xFF,
> +			       128 * sizeof(*sq));
>  		else
> -			memset(wqe, qp->swqe_polarity ? 0xFF : 0, 0x1000);
> +			memset(sq, qp->swqe_polarity ? 0xFF : 0,
> +			       128 * sizeof(*sq));
>  	}
>  }
> 
> --
Acked-by: Shiraz Saleem <shiraz.saleem@xxxxxxxxx>