linux-kernel - [PATCH] RDMA/hns: Use 64-bit arithmetic instead of 32-bit

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Date:   Thu, 18 Oct 2018 10:02:58 +0200
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Lijun Ou <oulijun@...wei.com>,
        "Wei Hu(Xavier)" <xavier.huwei@...wei.com>,
        Doug Ledford <dledford@...hat.com>,
        Jason Gunthorpe <jgg@...pe.ca>
Cc:     linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] RDMA/hns: Use 64-bit arithmetic instead of 32-bit

Cast *max_num_sg* to u64 in order to give the compiler complete
information about the proper arithmetic to use.

Notice that such variable is used in a context that expects an
expression of type u64 (64 bits, unsigned) and the following
expression is currently being evaluated using 32-bit
arithmetic:

length = max_num_sg * page_size;

Addresses-Coverity-ID: 1474517 ("Unintentional integer overflow")
Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/infiniband/hw/hns/hns_roce_mr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_mr.c b/drivers/infiniband/hw/hns/hns_roce_mr.c
index 521ad2a..d479d5e 100644
--- a/drivers/infiniband/hw/hns/hns_roce_mr.c
+++ b/drivers/infiniband/hw/hns/hns_roce_mr.c
@@ -1219,7 +1219,7 @@ struct ib_mr *hns_roce_alloc_mr(struct ib_pd *pd, enum ib_mr_type mr_type,
 	int ret;
 
 	page_size = 1 << (hr_dev->caps.pbl_buf_pg_sz + PAGE_SHIFT);
-	length = max_num_sg * page_size;
+	length = (u64)max_num_sg * page_size;
 
 	if (mr_type != IB_MR_TYPE_MEM_REG)
 		return ERR_PTR(-EINVAL);
-- 
2.7.4