CVE-2025-21972 Information

Description

In the Linux kernel the following vulnerability has been resolved:

net: mctp: unshare packets when reassembling

Ensure that the frag_list used for reassembly isn’t shared with other packets. This avoids incorrect reassembly when packets are cloned and prevents a memory leak due to circular references between fragments and their skb_shared_info.

The upcoming MCTP-over-USB driver uses skb_clone which can trigger the problem - other MCTP drivers don’t share SKBs.

A kunit test is added to reproduce the issue.

Reference

https://git.kernel.org/stable/c/5c47d5bfa7b096cf8890afac32141c578583f8e0 https://git.kernel.org/stable/c/f44fff3d3c6cd67b6f348b821d73c4d6888c7a6e https://git.kernel.org/stable/c/f5d83cf0eeb90fade4d5c4d17d24b8bee9ceeecc