In the Linux kernel, the following vulnerability has been resolved:
sctp: add a refcnt in sctp_stream_priorities to avoid a nested loop
With this refcnt added in sctp_stream_priorities, we dont need to traverse all streams to check if the prio is used by other streams when freeing one streams 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 doesnt need to use refcount_t type for this counter, as its accessing is always protected under the sock lock.
v1->v2: