Re: [PATCH net] net: lantiq_xrx200: fix use after free bug

From: Hauke Mehrtens
Date: Sat Mar 05 2022 - 10:41:21 EST


On 3/5/22 12:20, Aleksander Jan Bajkowski wrote:
The skb->len field is read after the packet is sent to the network
stack. In the meantime, skb can be freed. This patch fixes this bug.

Fixes: c3e6b2c35b34 ("net: lantiq_xrx200: add ingress SG DMA support")
Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Aleksander Jan Bajkowski <olek2@xxxxx>

Acked-by: Hauke Mehrtens <hauke@xxxxxxxxxx>

---
drivers/net/ethernet/lantiq_xrx200.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c
index 41d11137cde0..5712c3e94be8 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -260,9 +260,9 @@ static int xrx200_hw_receive(struct xrx200_chan *ch)
if (ctl & LTQ_DMA_EOP) {
ch->skb_head->protocol = eth_type_trans(ch->skb_head, net_dev);
- netif_receive_skb(ch->skb_head);
net_dev->stats.rx_packets++;
net_dev->stats.rx_bytes += ch->skb_head->len;
+ netif_receive_skb(ch->skb_head);
ch->skb_head = NULL;
ch->skb_tail = NULL;
ret = XRX200_DMA_PACKET_COMPLETE;