From dc1b438a35773d030be0ee80d9c635c3e558a322 Mon Sep 17 00:00:00 2001 From: Lv Yunlong Date: Mon, 26 Apr 2021 09:06:25 -0700 Subject: [PATCH] net:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send [ Upstream commit 6d72e7c767acbbdd44ebc7d89c6690b405b32b57 ] In emac_mac_tx_buf_send, it calls emac_tx_fill_tpd(..,skb,..). If some error happens in emac_tx_fill_tpd(), the skb will be freed via dev_kfree_skb(skb) in error branch of emac_tx_fill_tpd(). But the freed skb is still used via skb->len by netdev_sent_queue(,skb->len). As i observed that emac_tx_fill_tpd() haven't modified the value of skb->len, thus my patch assigns skb->len to 'len' before the possible free and use 'len' instead of skb->len later. Fixes: b9b17debc69d2 ("net: emac: emac gigabit ethernet controller driver") Signed-off-by: Lv Yunlong Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/ethernet/qualcomm/emac/emac-mac.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/qualcomm/emac/emac-mac.c b/drivers/net/ethernet/qualcomm/emac/emac-mac.c index 44f797ab5d15..57f509a6c449 100644 --- a/drivers/net/ethernet/qualcomm/emac/emac-mac.c +++ b/drivers/net/ethernet/qualcomm/emac/emac-mac.c @@ -1458,6 +1458,7 @@ int emac_mac_tx_buf_send(struct emac_adapter *adpt, struct emac_tx_queue *tx_q, { struct emac_tpd tpd; u32 prod_idx; + int len; memset(&tpd, 0, sizeof(tpd)); @@ -1477,9 +1478,10 @@ int emac_mac_tx_buf_send(struct emac_adapter *adpt, struct emac_tx_queue *tx_q, if (skb_network_offset(skb) != ETH_HLEN) TPD_TYP_SET(&tpd, 1); + len = skb->len; emac_tx_fill_tpd(adpt, tx_q, skb, &tpd); - netdev_sent_queue(adpt->netdev, skb->len); + netdev_sent_queue(adpt->netdev, len); /* Make sure the are enough free descriptors to hold one * maximum-sized SKB. We need one desc for each fragment, -- 2.20.1