CVE-2021-47013

Description

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.

CVSS breakdown

Affected products

• Linux / Linux5.10.37 – 5.10.*
• Linux / Linux5.11.21 – 5.11.*
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – c7f75d11fe72913d2619f97b2334b083cd7bb955
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – dc1b438a35773d030be0ee80d9c635c3e558a322
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – 16d8c44be52e3650917736d45f5904384a9da834
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – 55fcdd1258faaecca74b91b88cc0921f9edd775d
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – 9dc373f74097edd0e35f3393d6248eda8d1ba99d
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – 8c06f34785068b87e2b560534c77c163d6c6dca7
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – e407495ba6788a67d1bd41714158c079e340879b
• Linux / Linuxb9b17debc69d27cd55e21ee51a5ba7fc50a426cf – 6d72e7c767acbbdd44ebc7d89c6690b405b32b57
• Linux / Linux4.9 – 4.9
• Linux / Linux0 – 4.9
• Linux / Linux4.9.269 – 4.9.*
• Linux / Linux4.14.233 – 4.14.*
• Linux / Linux4.19.191 – 4.19.*
• Linux / Linux5.4.119 – 5.4.*
• Linux / Linux5.12.4 – 5.12.*
• Linux / Linux5.13 – *
• Linux / Linux kernel4.9 – 4.9.269

References

• MISChttps://git.kernel.org/stable/c/c7f75d11fe72913d2619f97b2334b083cd7bb955
• MISChttps://git.kernel.org/stable/c/dc1b438a35773d030be0ee80d9c635c3e558a322
• MISChttps://git.kernel.org/stable/c/16d8c44be52e3650917736d45f5904384a9da834
• MISChttps://git.kernel.org/stable/c/55fcdd1258faaecca74b91b88cc0921f9edd775d
• MISChttps://git.kernel.org/stable/c/9dc373f74097edd0e35f3393d6248eda8d1ba99d
• MISChttps://git.kernel.org/stable/c/8c06f34785068b87e2b560534c77c163d6c6dca7
• MISChttps://git.kernel.org/stable/c/e407495ba6788a67d1bd41714158c079e340879b
• MISChttps://git.kernel.org/stable/c/6d72e7c767acbbdd44ebc7d89c6690b405b32b57