CVE-2026-80866 is a vulnerability in Linux Kernel
Published on September 4, 2026
tipc: avoid busy looping in tipc_exit_net()
In the Linux kernel, the following vulnerability has been resolved:
tipc: avoid busy looping in tipc_exit_net()
Blamed commit introduced a busy-wait loop in tipc_exit_net()
to wait for pending UDP bearer cleanup works to complete:
while (atomic_read(&tn->wq_count))
cond_resched();
This loop can busy-wait for a long time if cond_resched() is a NOP. This
typically happens if the netns exit is executed by a high priority task,
or under kernels configured without preemption (CONFIG_PREEMPT_NONE). In
such cases, it wastes CPU cycles and can lead to soft lockups.
Fix this by replacing the busy loop with wait_var_event(), allowing the
thread to sleep properly until the work queue count reaches zero.
Accordingly, update cleanup_bearer() to use atomic_dec_and_test() and
wake_up_var() to wake up the waiter when the count drops to zero.
This uses the global wait queue hash table, avoiding the need to bloat
struct tipc_net with a wait_queue_head_t. The atomic_dec_and_test()
provides the necessary memory barrier to ensure the wakeup is not missed.
Products Associated with CVE-2026-80866
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Affected Versions
Linux:- Version 04c26faa51d1e2fe71cf13c45791f5174c37f986 and below 522d1d950b9e3b68190a6de7534827c8dccedb73 is affected.
- Version 04c26faa51d1e2fe71cf13c45791f5174c37f986 and below c1481c94e74c955e0448ddf46b8615a44d840c1e is affected.
- Version d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa is affected.
- Version 5195ec5e365a2a9331bfeb585b613a6e94f98dba is affected.
- Version b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d is affected.
- Version 5.4.124 and below 5.5 is affected.
- Version 5.10.42 and below 5.11 is affected.
- Version 5.12.9 and below 5.13 is affected.
- Version 5.13 is affected.
- Before 5.13 is unaffected.
- Version 7.1.5, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.