[PATCH net] net: hns3: fix double free issue for tx spare buffer

[Jijie Shao]

From: Jian Shen <shenjian15@xxxxxxxxxx>

The driver missed to clear ring->tx_spare to NULL when
fail to initialize tx spare buffer. And it will try to
free the tx spare buffer in hns3_fini_ring() if tx_spare
is not NULL. So it may cause double free issue.

Fixes: 907676b130711 ("net: hns3: use tx bounce buffer for small packets")
Signed-off-by: Jian Shen <shenjian15@xxxxxxxxxx>
Signed-off-by: Jijie Shao <shaojijie@xxxxxxxxxx>
---
 drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 7a9573dcab74..e879b04e21b0 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -1048,13 +1048,13 @@ static void hns3_init_tx_spare_buffer(struct hns3_enet_ring *ring)
 	int order;
 
 	if (!alloc_size)
-		return;
+		goto not_init;
 
 	order = get_order(alloc_size);
 	if (order > MAX_PAGE_ORDER) {
 		if (net_ratelimit())
 			dev_warn(ring_to_dev(ring), "failed to allocate tx spare buffer, exceed to max order\n");
-		return;
+		goto not_init;
 	}
 
 	tx_spare = devm_kzalloc(ring_to_dev(ring), sizeof(*tx_spare),
@@ -1092,6 +1092,13 @@ static void hns3_init_tx_spare_buffer(struct hns3_enet_ring *ring)
 	devm_kfree(ring_to_dev(ring), tx_spare);
 devm_kzalloc_error:
 	ring->tqp->handle->kinfo.tx_spare_buf_size = 0;
+not_init:
+	/* When driver init or reset_init, the ring->tx_spare is always NULL;
+	 * but when called from hns3_set_ringparam, it's usually not NULL, and
+	 * will be restored if hns3_init_all_ring() failed. So it's safe to set
+	 * ring->tx_spare to NULL here.
+	 */
+	ring->tx_spare = NULL;
 }
 
 /* Use hns3_tx_spare_space() to make sure there is enough buffer
-- 
2.33.0