[PATCH 5.4 26/60] mt76: dma: fix a possible memory leak in mt76_add_fragment()

[Greg Kroah-Hartman]

From: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>

[ Upstream commit 93a1d4791c10d443bc67044def7efee2991d48b7 ]

Fix a memory leak in mt76_add_fragment routine returning the buffer
to the page_frag_cache when we receive a new fragment and the
skb_shared_info frag array is full.

Fixes: b102f0c522cf6 ("mt76: fix array overflow on receiving too many fragments for a packet")
Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
Acked-by: Felix Fietkau <nbd@xxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/4f9dd73407da88b2a552517ce8db242d86bf4d5c.1611616130.git.lorenzo@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/wireless/mediatek/mt76/dma.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c
index 026d996612fbe..781952b686ed2 100644
--- a/drivers/net/wireless/mediatek/mt76/dma.c
+++ b/drivers/net/wireless/mediatek/mt76/dma.c
@@ -452,15 +452,17 @@ static void
 mt76_add_fragment(struct mt76_dev *dev, struct mt76_queue *q, void *data,
 		  int len, bool more)
 {
-	struct page *page = virt_to_head_page(data);
-	int offset = data - page_address(page);
 	struct sk_buff *skb = q->rx_head;
 	struct skb_shared_info *shinfo = skb_shinfo(skb);
 
 	if (shinfo->nr_frags < ARRAY_SIZE(shinfo->frags)) {
-		offset += q->buf_offset;
+		struct page *page = virt_to_head_page(data);
+		int offset = data - page_address(page) + q->buf_offset;
+
 		skb_add_rx_frag(skb, shinfo->nr_frags, page, offset, len,
 				q->buf_size);
+	} else {
+		skb_free_frag(data);
 	}
 
 	if (more)
-- 
2.27.0