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net:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send 

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: b9b17debc6 ("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>
This commit is contained in:
Lv Yunlong 2021-04-26 09:06:25 -07:00 committed by David S. Miller
parent f77bd544a6
commit 6d72e7c767
1 changed files with 3 additions and 1 deletions
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4
drivers/net/ethernet/qualcomm/emac/emac-mac.c
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@ -1437,6 +1437,7 @@ netdev_tx_t emac_mac_tx_buf_send(struct emac_adapter *adpt,
{
struct emac_tpd tpd;
u32 prod_idx;
int len;
memset(&tpd, 0, sizeof(tpd));
@ -1456,9 +1457,10 @@ netdev_tx_t emac_mac_tx_buf_send(struct emac_adapter *adpt,
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,