This is a note to let you know that I've just added the patch titled net:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-emac-emac-mac-fix-a-use-after-free-in-emac_mac_t.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f6e43a0014a204249734f25cc0cc5dd45826cc09 Author: Lv Yunlong <lyl2019@xxxxxxxxxxxxxxxx> Date: Mon Apr 26 09:06:25 2021 -0700 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 <lyl2019@xxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/qualcomm/emac/emac-mac.c b/drivers/net/ethernet/qualcomm/emac/emac-mac.c index 117188e3c7de..87b8c032195d 100644 --- a/drivers/net/ethernet/qualcomm/emac/emac-mac.c +++ b/drivers/net/ethernet/qualcomm/emac/emac-mac.c @@ -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,