netdev - [PATCH net V4 5/5] net/smc: use after free fix in smc_wr_tx_put

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Message-Id: <20181120154643.24111-6-ubraun@linux.ibm.com>
Date:   Tue, 20 Nov 2018 16:46:43 +0100
From:   Ursula Braun <ubraun@...ux.ibm.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-s390@...r.kernel.org,
        schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
        raspl@...ux.ibm.com, ubraun@...ux.ibm.com
Subject: [PATCH net V4 5/5] net/smc: use after free fix in smc_wr_tx_put_slot()

From: Ursula Braun <ursula.braun@...ux.ibm.com>

In smc_wr_tx_put_slot() field pend->idx is used after being
cleared. That means always idx 0 is cleared in the wr_tx_mask.
This results in a broken administration of available WR send
payload buffers.

Signed-off-by: Ursula Braun <ubraun@...ux.ibm.com>
---
 net/smc/smc_wr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c
index 3c458d279855..c2694750a6a8 100644
--- a/net/smc/smc_wr.c
+++ b/net/smc/smc_wr.c
@@ -215,12 +215,14 @@ int smc_wr_tx_put_slot(struct smc_link *link,
 
 	pend = container_of(wr_pend_priv, struct smc_wr_tx_pend, priv);
 	if (pend->idx < link->wr_tx_cnt) {
+		u32 idx = pend->idx;
+
 		/* clear the full struct smc_wr_tx_pend including .priv */
 		memset(&link->wr_tx_pends[pend->idx], 0,
 		       sizeof(link->wr_tx_pends[pend->idx]));
 		memset(&link->wr_tx_bufs[pend->idx], 0,
 		       sizeof(link->wr_tx_bufs[pend->idx]));
-		test_and_clear_bit(pend->idx, link->wr_tx_mask);
+		test_and_clear_bit(idx, link->wr_tx_mask);
 		return 1;
 	}
 
-- 
2.16.4