On Wed, Feb 15, 2023 at 03:04:44PM -0500, Xin Long wrote:

With this refcnt added in sctp_stream_priorities, we don't need to
traverse all streams to check if the prio is used by other streams
when freeing one stream's prio in sctp_sched_prio_free_sid(). This
can avoid a nested loop (up to 65535 * 65535), which may cause a
stuck as Ying reported:

    watchdog: BUG: soft lockup - CPU#23 stuck for 26s! [ksoftirqd/23:136]
    Call Trace:
     <TASK>
     sctp_sched_prio_free_sid+0xab/0x100 [sctp]
     sctp_stream_free_ext+0x64/0xa0 [sctp]
     sctp_stream_free+0x31/0x50 [sctp]
     sctp_association_free+0xa5/0x200 [sctp]

Note that it doesn't need to use refcount_t type for this counter,
as its accessing is always protected under the sock lock.

Fixes: 9ed7bfc79542 ("sctp: fix memory leak in sctp_stream_outq_migrate()")
Reported-by: Ying Xu <redacted>
Signed-off-by: Xin Long <lucien.xin@gmail.com>

Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>