RDMA/hfi1: Fix potential integer multiplication overflow errors

commit f93e91a upstream.

When multiplying of different types, an overflow is possible even when
storing the result in a larger type. This is because the conversion is
done after the multiplication. So arithmetic overflow and thus in
incorrect value is possible.

Correct an instance of this in the inter packet delay calculation.  Fix by
ensuring one of the operands is u64 which will promote the other to u64 as
well ensuring no overflow.

Cc: [email protected]
Fixes: 7724105 ("IB/hfi1: add driver files")
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Marciniszyn <[email protected]>
Signed-off-by: Dennis Dalessandro <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: ddalessa

drivers/infiniband/hw/hfi1/init.c

@@ -489,7 +489,7 @@ void set_link_ipg(struct hfi1_pportdata *ppd)
 	u16 shift, mult;
 	u64 src;
 	u32 current_egress_rate; /* Mbits /sec */
-	u32 max_pkt_time;
+	u64 max_pkt_time;
 	/*
 	 * max_pkt_time is the maximum packet egress time in units
 	 * of the fabric clock period 1/(805 MHz).