CVE-2021-47132

In the Linux kernel, the following vulnerability has been resolved: mptcp:
fix sk_forward_memory corruption on retransmission MPTCP sk_forward_memory
handling is a bit special, as such field is protected by the msk socket
spin_lock, instead of the plain socket lock. Currently we have a code path
updating such field without handling the relevant lock: __mptcp_retrans()
-> __mptcp_clean_una_wakeup() Several helpers in __mptcp_clean_una_wakeup()
will update sk_forward_alloc, possibly causing such field corruption, as
reported by Matthieu. Address the issue providing and using a new variant
of blamed function which explicitly acquires the msk spin lock.

Bugs

• <https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2021-47132&gt;