[PATCH 5.2 130/162] IB/hfi1: Unsafe PSN checking for TID RDMA READ Resp packet

[Greg Kroah-Hartman]

From: Kaike Wan <kaike.wan@xxxxxxxxx>

commit 35d5c8b82e2c32e8e29ca195bb4dac60ba7d97fc upstream.

When processing a TID RDMA READ RESP packet that causes KDETH EFLAGS
errors, the packet's IB PSN is checked against qp->s_last_psn and
qp->s_psn without the protection of qp->s_lock, which is not safe.

This patch fixes the issue by acquiring qp->s_lock first.

Fixes: 9905bf06e890 ("IB/hfi1: Add functions to receive TID RDMA READ response")
Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
Signed-off-by: Kaike Wan <kaike.wan@xxxxxxxxx>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>
Link: https://lore.kernel.org/r/20190815192039.105923.7852.stgit@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/hw/hfi1/tid_rdma.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/hw/hfi1/tid_rdma.c
+++ b/drivers/infiniband/hw/hfi1/tid_rdma.c
@@ -2689,12 +2689,12 @@ static bool handle_read_kdeth_eflags(str
 	u32 fpsn;
 
 	lockdep_assert_held(&qp->r_lock);
+	spin_lock(&qp->s_lock);
 	/* If the psn is out of valid range, drop the packet */
 	if (cmp_psn(ibpsn, qp->s_last_psn) < 0 ||
 	    cmp_psn(ibpsn, qp->s_psn) > 0)
-		return ret;
+		goto s_unlock;
 
-	spin_lock(&qp->s_lock);
 	/*
 	 * Note that NAKs implicitly ACK outstanding SEND and RDMA write
 	 * requests and implicitly NAK RDMA read and atomic requests issued