net/smc: fix using of uninitialized completions

[ Upstream commit 6d7373da ]

In smc_wr_tx_send_wait() the completion on index specified by
pend->idx is initialized and after smc_wr_tx_send() was called the wait
for completion starts. pend->idx is used to get the correct index for
the wait, but the pend structure could already be cleared in
smc_wr_tx_process_cqe().
Introduce pnd_idx to hold and use a local copy of the correct index.

Fixes: 09c61d24 ("net/smc: wait for departure of an IB message")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/smc/smc_wr.c

@@ -288,18 +288,20 @@ int smc_wr_tx_send_wait(struct smc_link *link, struct smc_wr_tx_pend_priv *priv,
 			unsigned long timeout)
 {
 	struct smc_wr_tx_pend *pend;
+	u32 pnd_idx;
 	int rc;
 
 	pend = container_of(priv, struct smc_wr_tx_pend, priv);
 	pend->compl_requested = 1;
-	init_completion(&link->wr_tx_compl[pend->idx]);
+	pnd_idx = pend->idx;
+	init_completion(&link->wr_tx_compl[pnd_idx]);
 
 	rc = smc_wr_tx_send(link, priv);
 	if (rc)
 		return rc;
 	/* wait for completion by smc_wr_tx_process_cqe() */
 	rc = wait_for_completion_interruptible_timeout(
-					&link->wr_tx_compl[pend->idx], timeout);
+					&link->wr_tx_compl[pnd_idx], timeout);
 	if (rc <= 0)
 		rc = -ENODATA;
 	if (rc > 0)