CVE-2021-47013: Linux Kernel

High severity, CVSS 7.8. EPSS: 0.8% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: 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.

Affected products

• Linux Linux Kernel: from 4.9, before 4.9.269 (fixed in 4.9.269); from 4.10, before 4.14.233 (fixed in 4.14.233); from 4.15, before 4.19.191 (fixed in 4.19.191); from 4.20, before 5.4.119 (fixed in 5.4.119); from 5.5, before 5.10.37 (fixed in 5.10.37); from 5.11, before 5.11.21 (fixed in 5.11.21); …

Published 2024-02-28. Last modified 2026-08-04.