[PATCH] RDMA/siw: Fix potential siw_mem refcnt leak in nr_add_node

[Xiyu Yang]

siw_fastreg_mr() invokes siw_mem_id2obj(), which returns a local
reference of the siw_mem object to "mem" with increased refcnt.
When siw_fastreg_mr() returns, "mem" becomes invalid, so the refcount
should be decreased to keep refcount balanced.

The issue happens in one error path of siw_fastreg_mr(). When "base_mr"
equals to NULL but "mem" is not NULL, the function forgets to decrease
the refcnt increased by siw_mem_id2obj() and causes a refcnt leak.

Fix this issue by calling siw_mem_put() on this error path when mem is
not NULL.

Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx>
Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx>
---
 drivers/infiniband/sw/siw/siw_qp_tx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c
index ae92c8080967..86044a44b83b 100644
--- a/drivers/infiniband/sw/siw/siw_qp_tx.c
+++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
@@ -926,6 +926,8 @@ static int siw_fastreg_mr(struct ib_pd *pd, struct siw_sqe *sqe)
 	siw_dbg_pd(pd, "STag 0x%08x\n", sqe->rkey);
 
 	if (unlikely(!mem || !base_mr)) {
+		if (mem)
+			siw_mem_put(mem);
 		pr_warn("siw: fastreg: STag 0x%08x unknown\n", sqe->rkey);
 		return -EINVAL;
 	}
-- 
2.7.4