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List:       linux-rdma
Subject:    Re: mlx5 attr.max_sge checks
From:       Leon Romanovsky <leon () kernel ! org>
Date:       2023-12-20 8:07:29
Message-ID: 20231220080729.GB136797 () unreal
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On Tue, Dec 19, 2023 at 09:56:01PM +0300, listdansp wrote:
> Hi,
> 
> While investigating the one report of the static analyzer (svacer), it was
> discovered that attr.max_sge was not checked for the maximum value in the
> mlx5_ib_create_srq function. However, this check is present in
> https://github.com/linux-rdma/rdma-core. Also, checks are present in most
> other infiniband Linux Kernel drivers. This may lead to incorrect driver
> operation for example
> int mlx5_ib_read_wqe_srq(struct mlx5_ib_srq *srq, int wqe_index, void
> *buffer, size_tbuflen, size_t*bc)
> {
> structib_umem*umem= srq->umem;
> size_twqe_size= 1 << srq->msrq.wqe_shift; // integeroverflowhere
> if(buflen< wqe_size)
> return-EINVAL;
> In my opinion, the only possible solution to this problem may be to add a
> check to mlx5_ib_create_srq similar to
> https://github.com/linux-rdma/rdma-core
> <https://github.com/linux-rdma/rdma-core> like
> u32 max_sge= MLX5_CAP_GEN(dev->mdev, max_wqe_sz_rq) /
> sizeof(structmlx5_wqe_data_seg);
> if (attr->attr.max_sge > max_sge) {
> mlx5_ib_dbg
> <https://elixir.bootlin.com/linux/v5.10.169/C/ident/mlx5_ib_dbg>(dev,
> "max_sge%d, cap %d\n", init_attr
> <https://elixir.bootlin.com/linux/v5.10.169/C/ident/init_attr>->attr.max_
> <https://elixir.bootlin.com/linux/v5.10.169/C/ident/max_wr>sge, max_sge);
> return -EINVAL <https://elixir.bootlin.com/linux/v5.10.169/C/ident/EINVAL>;
> }
> 
> I would appreciate your suggestions and comments.

Can you please provide an example of such values?

At least in the presented case, the values are supplied by FW and are
supposed to be right without any overflows.

Thanks

> 
> Best regards,
> Danila
> 
> 

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