[PATCH] IB/rdmavt: Fix target union member for rvt_post_one_wr()

[Kees Cook]

The "cplen" result used by the memcpy() into struct rvt_swqe "wqe" may
be sized to 80 for struct rvt_ud_wr (which is member "ud_wr", not "wr"
which is only 40 bytes in size). Change the destination union member so
the compiler can use the correct bounds check.

struct rvt_swqe {
        union {
                struct ib_send_wr wr;   /* don't use wr.sg_list */
                struct rvt_ud_wr ud_wr;
		...
	};
	...
};

Silences false positive memcpy() run-time warning:

  memcpy: detected field-spanning write (size 80) of single field "&wqe->wr" at drivers/infiniband/sw/rdmavt/qp.c:2043 (size 40)

Reported-by: Zhang Yi <yizhan@xxxxxxxxxx>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216561
Cc: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: linux-rdma@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/infiniband/sw/rdmavt/qp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
index 3acab569fbb9..3f707e1fa517 100644
--- a/drivers/infiniband/sw/rdmavt/qp.c
+++ b/drivers/infiniband/sw/rdmavt/qp.c
@@ -2040,7 +2040,7 @@ static int rvt_post_one_wr(struct rvt_qp *qp,
 	wqe = rvt_get_swqe_ptr(qp, qp->s_head);
 
 	/* cplen has length from above */
-	memcpy(&wqe->wr, wr, cplen);
+	memcpy(&wqe->ud_wr, wr, cplen);
 
 	wqe->length = 0;
 	j = 0;
-- 
2.34.1