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

[Bernard Metzler]

-----linux-rdma-owner@xxxxxxxxxxxxxxx wrote: -----

>To: "Bernard Metzler" <bmt@xxxxxxxxxxxxxx>, "Doug Ledford"
><dledford@xxxxxxxxxx>, "Jason Gunthorpe" <jgg@xxxxxxxx>,
>linux-rdma@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
>From: "Xiyu Yang" 
>Sent by: linux-rdma-owner@xxxxxxxxxxxxxxx
>Date: 04/15/2020 10:46AM
>Cc: yuanxzhang@xxxxxxxxxxxx, kjlu@xxxxxxx, "Xiyu Yang"
><xiyuyang19@xxxxxxxxxxxx>, "Xin Tan" <tanxin.ctf@xxxxxxxxx>
>Subject: [EXTERNAL] [PATCH] RDMA/siw: Fix potential siw_mem refcnt
>leak in nr_add_node
>
>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;
> 	}
>-- 

I agree - thanks for the fix!


Reviewed-by: Bernard Metzler <bmt@xxxxxxxxxxxxxx>