RDMA/siw: Set defined status for work completion with undefined status

[ Upstream commit 60da2d1 ]

A malicious user may write undefined values into memory mapped completion
queue elements status or opcode. Undefined status or opcode values will
result in out-of-bounds access to an array mapping siw internal
representation of opcode and status to RDMA core representation when
reaping CQ elements. While siw detects those undefined values, it did not
correctly set completion status to a defined value, thus defeating the
whole purpose of the check.

This bug leads to the following Smatch static checker warning:

	drivers/infiniband/sw/siw/siw_cq.c:96 siw_reap_cqe()
	error: buffer overflow 'map_cqe_status' 10 <= 21

Fixes: bdf1da5 ("RDMA/siw: Fix immediate work request flush to completion queue")
Link: https://lore.kernel.org/r/20221115170747.1263298-1-bmt@zurich.ibm.com
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/infiniband/sw/siw/siw_cq.c

@@ -88,9 +88,9 @@ int siw_reap_cqe(struct siw_cq *cq, struct ib_wc *wc)
 
 			if (opcode >= SIW_NUM_OPCODES) {
 				opcode = 0;
-				status = IB_WC_GENERAL_ERR;
+				status = SIW_WC_GENERAL_ERR;
 			} else if (status >= SIW_NUM_WC_STATUS) {
-				status = IB_WC_GENERAL_ERR;
+				status = SIW_WC_GENERAL_ERR;
 			}
 			wc->opcode = map_wc_opcode[opcode];
 			wc->status = map_cqe_status[status].ib;