[PATCH v2 net 9/9] net: enetc: fix the off-by-one issue in enetc_map_tx_tso_buffs()

[Wei Fang]

There is an off-by-one issue for the err_chained_bd path, it will free
one more tx_swbd than expected. But there is no such issue for the
err_map_data path. To fix this off-by-one issue and make the two error
handling consistent, the loop condition of error handling is modified
and the 'count++' operation is moved before enetc_map_tx_tso_data().

Fixes: fb8629e2cbfc ("net: enetc: add support for software TSO")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
---
 drivers/net/ethernet/freescale/enetc/enetc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c
index 9a24d1176479..fe3967268a19 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc.c
@@ -832,6 +832,7 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb
 			txbd = ENETC_TXBD(*tx_ring, i);
 			tx_swbd = &tx_ring->tx_swbd[i];
 			prefetchw(txbd);
+			count++;
 
 			/* Compute the checksum over this segment of data and
 			 * add it to the csum already computed (over the L4
@@ -848,7 +849,6 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb
 				goto err_map_data;
 
 			data_len -= size;
-			count++;
 			bd_data_num++;
 			tso_build_data(skb, &tso, size);
 
@@ -874,13 +874,13 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff *skb
 	dev_err(tx_ring->dev, "DMA map error");
 
 err_chained_bd:
-	do {
+	while (count--) {
 		tx_swbd = &tx_ring->tx_swbd[i];
 		enetc_free_tx_frame(tx_ring, tx_swbd);
 		if (i == 0)
 			i = tx_ring->bd_count;
 		i--;
-	} while (count--);
+	}
 
 	return 0;
 }
-- 
2.34.1