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

mptcp: ensure snd_una is properly initialized on connect

This is strictly related to commit fb7a0d334894 ("mptcp: ensure snd_nxt
is properly initialized on connect"). It turns out that syzkaller can
trigger the retransmit after fallback and before processing any other
incoming packet - so that snd_una is still left uninitialized.

Address the issue explicitly initializing snd_una together with snd_nxt
and write_seq.

References

• https://nvd.nist.gov/vuln/detail/CVE-2024-40931
• https://git.kernel.org/stable/c/208cd22ef5e57f82d38ec11c1a1703f9401d6dde
• https://git.kernel.org/stable/c/7b9c7fc8600b64a86e4b47b2d190bba380267726
• https://git.kernel.org/stable/c/8031b58c3a9b1db3ef68b3bd749fbee2e1e1aaa3
• https://git.kernel.org/stable/c/ef473bf1dd7e8dd08bcc04b9e2d1bfed69a0a7ce
• https://git.kernel.org/stable/c/f03c46eabb3a67bd2993e237ab5517f00a5f1813
• https://git.kernel.org/stable/c/f1f0a46f8bb8890b90ab7194f0a0c8fe2a3fb57f