IB/srp: fix invalid indirect_sg_entries parameter value

After setting indirect_sg_entries module_param to huge value (e.g 500,000),
srp_alloc_req_data() fails to allocate indirect descriptors for the request
ring (kmalloc fails). This commit enforces the maximum value of
indirect_sg_entries to be SG_MAX_SEGMENTS as signified in module param
description.

Fixes: 65e8617fba17 (scsi: rename SCSI_MAX_{SG, SG_CHAIN}_SEGMENTS)
Fixes: c07d424d6118 (IB/srp: add support for indirect tables that don't fit in SRP_CMD)
Cc: stable@vger.kernel.org # 4.7+
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>--
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -3699,6 +3699,12 @@ static int __init srp_init_module(void)
 		indirect_sg_entries = cmd_sg_entries;
 	}
 
+	if (indirect_sg_entries > SG_MAX_SEGMENTS) {
+		pr_warn("Clamping indirect_sg_entries to %u\n",
+			SG_MAX_SEGMENTS);
+		indirect_sg_entries = SG_MAX_SEGMENTS;
+	}
+
 	srp_remove_wq = create_workqueue("srp_remove");
 	if (!srp_remove_wq) {
 		ret = -ENOMEM;