Commit 16d8c44b authored Apr 26, 2021 by Lv Yunlong Committed by Greg Kroah-Hartman May 22, 2021

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: b9b17deb ("net: emac: emac gigabit ethernet controller driver")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 35385daa

drivers/net/ethernet/qualcomm/emac/emac-mac.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1449,6 +1449,7 @@ 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));

		@@ -1468,9 +1469,10 @@ 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,