CVE-2026-97568

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CVE-2026-97568
In the Linux kernel, the following vulnerability has been resolved:

mptcp: syncookies: remember the request backup flag

Instead of using an uninitialised bit when copying the info in
subflow_ulp_clone().

To fix this, no need to extend the join_entry structure: backup is
coming from struct mptcp_subflow_request_sock, only one bit. Do the same
here by using one bit for both.