RDMA/ionic: Fix kernel stack leak in ionic_create_cq()

struct ionic_cq_resp resp {
    __u32 cqid[2];         // offset 0 - PARTIALLY SET (see below)
    __u8  udma_mask;       // offset 8 - SET (resp.udma_mask = vcq->udma_mask)
    __u8  rsvd[7];         // offset 9 - NEVER SET <- LEAK
};

rsvd[7]: 7 bytes of stack memory leaked unconditionally.

cqid[2]: The loop at line 1256 iterates over udma_idx but skips indices
where !(vcq->udma_mask & BIT(udma_idx)). The array has 2 entries but
udma_count could be 1, meaning cqid[1] might never be written via
ionic_create_cq_common(). If udma_mask only has bit 0 set, cqid[1] (4
bytes) is also leaked. So potentially 11 bytes leaked.

Cc: stable@vger.kernel.org
Fixes: e852182 ("RDMA/ionic: Register device ops for control path")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://patch.msgid.link/4-v1-83e918d69e73+a9-rdma_udata_rc_jgg@nvidia.com
Acked-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: jgunthorpe

drivers/infiniband/hw/ionic/ionic_controlpath.c

@@ -1218,7 +1218,7 @@ int ionic_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
 		rdma_udata_to_drv_context(udata, struct ionic_ctx, ibctx);
 	struct ionic_vcq *vcq = to_ionic_vcq(ibcq);
 	struct ionic_tbl_buf buf = {};
-	struct ionic_cq_resp resp;
+	struct ionic_cq_resp resp = {};
 	struct ionic_cq_req req;
 	int udma_idx = 0, rc;