sctp: avoid livelock while updating retransmit path

sctp_assoc_update_retran_path() can loop forever when every remaining
transport, including retran_path, is SCTP_UNCONFIRMED: the state check
runs before the wraparound test, so the loop cannot observe that it has
completed a full pass.

Fix this by considering a transport only when it is not UNCONFIRMED,
then checking whether the walk has returned to retran_path. This makes
the full-pass termination independent of the transport state while
preserving the existing fallback selection semantics.

Also restore the NULL guard around the retran_path assignment. In the
all-UNCONFIRMED case there is no eligible replacement transport, and
installing NULL would leave later retransmit-path users and the debug
print with a NULL path.

Fixes: 4c47af4d5eb2 ("net: sctp: rework multihoming retransmission path selection to rfc4960")
Signed-off-by: Yiqi Sun <sunyiqixm@gmail.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20260915095017.942213-1-sunyiqixm@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions