[bug report] RDMA/erdma: Add verbs implementation

[Dan Carpenter <dan.carpenter@linaro.org>]

Hello Cheng Xu,

The patch 155055771704: "RDMA/erdma: Add verbs implementation" from
Jul 27, 2022 (linux-next), leads to the following Smatch static
checker warning:

	drivers/infiniband/hw/erdma/erdma_verbs.c:1044 erdma_get_dma_mr()
	error: potential zalloc NULL dereference: 'mr->mem.mtt'

drivers/infiniband/hw/erdma/erdma_verbs.c
    1023 struct ib_mr *erdma_get_dma_mr(struct ib_pd *ibpd, int acc)
    1024 {
    1025         struct erdma_dev *dev = to_edev(ibpd->device);
    1026         struct erdma_mr *mr;
    1027         u32 stag;
    1028         int ret;
    1029 
    1030         mr = kzalloc(sizeof(*mr), GFP_KERNEL);
    1031         if (!mr)
    1032                 return ERR_PTR(-ENOMEM);
    1033 
    1034         ret = erdma_create_stag(dev, &stag);
    1035         if (ret)
    1036                 goto out_free;
    1037 
    1038         mr->type = ERDMA_MR_TYPE_DMA;
    1039 
    1040         mr->ibmr.lkey = stag;
    1041         mr->ibmr.rkey = stag;
    1042         mr->ibmr.pd = ibpd;
    1043         mr->access = ERDMA_MR_ACC_LR | to_erdma_access_flags(acc);
--> 1044         ret = regmr_cmd(dev, mr);

The "mr->mem.mtt" pointer is NULL here so regmr_cmd() will crash.  There
are three callers and the other two are correct.

    1045         if (ret)
    1046                 goto out_remove_stag;
    1047 
    1048         return &mr->ibmr;
    1049 
    1050 out_remove_stag:
    1051         erdma_free_idx(&dev->res_cb[ERDMA_RES_TYPE_STAG_IDX],
    1052                        mr->ibmr.lkey >> 8);
    1053 
    1054 out_free:
    1055         kfree(mr);
    1056 
    1057         return ERR_PTR(ret);
    1058 }

regards,
dan carpenter