[PATCH AUTOSEL 5.4 043/108] mt76: fix handling full tx queues in mt76_dma_tx_queue_skb_raw

Sasha Levin
2020-04-11T23:30:32Z

From: Felix Fietkau <nbd@nbd.name>

[ Upstream commit 93eaec7625f13cffb593b471405b017c7e64d4ee ]

Fixes a theoretical issue where it could potentially overwrite an existing
descriptor entry (and leaking its skb)

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/mediatek/mt76/dma.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index 6249a46c19762..026d996612fbe 100644
--- a/drivers/net/wireless/mediatek/mt76/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/dma.c
@@ -261,10 +261,13 @@ mt76_dma_tx_queue_skb_raw(struct mt76_dev *dev, enum mt76_txq_id qid,
struct mt76_queue_buf buf;
dma_addr_t addr;

+ if (q->queued + 1 >= q->ndesc - 1)
+ goto error;
+
addr = dma_map_single(dev->dev, skb->data, skb->len,
DMA_TO_DEVICE);
if (unlikely(dma_mapping_error(dev->dev, addr)))
- return -ENOMEM;
+ goto error;

buf.addr = addr;
buf.len = skb->len;
@@ -275,6 +278,10 @@ mt76_dma_tx_queue_skb_raw(struct mt76_dev *dev, enum mt76_txq_id qid,
spin_unlock_bh(&q->lock);

return 0;
+
+error:
+ dev_kfree_skb(skb);
+ return -ENOMEM;
}

static int
--
2.20.1