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Deadlock Affecting rv package, versions *

Severity

 Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.18% (9th percentile)

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  • Snyk IDSNYK-CENTOS10-RV-17605278
  • published27 Jun 2026
  • disclosed24 Jun 2026
Report a new vulnerability Found a mistake?

Introduced: 24 Jun 2026

NewCVE-2026-52946  (opens in a new tab)
CWE-833  (opens in a new tab)

How to fix?

There is no fixed version for Centos:10 rv.

NVD Description

Note: Versions mentioned in the description apply only to the upstream rv package and not the rv package as distributed by Centos. See How to fix? for Centos:10 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling

A SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in send_sigio() and send_sigurg() when a process group receives a signal.

When FASYNC is configured for a process group (PIDTYPE_PGID), both functions use read_lock(&tasklist_lock) to traverse the task list. However, they are frequently called from softirq context:

  • send_sigio() via input_inject_event -> kill_fasync
  • send_sigurg() via tcp_check_urg -> sk_send_sigurg (NET_RX_SOFTIRQ)

The deadlock is caused by the rwlock writer fairness mechanism:

  1. CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait().
  2. CPU 1 (process context) attempts write_lock(&tasklist_lock) in fork() or exit() and spins, which blocks all new readers.
  3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception).
  4. The softirq calls send_sigurg() and attempts to acquire read_lock(&tasklist_lock), deadlocking because CPU 1 is waiting.

Since PID hashing and do_each_pid_task() traversals are already RCU-protected, the read_lock on tasklist_lock is no longer strictly required for safe traversal. Fix this by replacing tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path. This also mitigates a potential remote denial of service vector via TCP URG packets.

Lockdep splat:

WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [...] Chain exists of: &dev->event_lock --> &f_owner->lock --> tasklist_lock

Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tasklist_lock); local_irq_disable(); lock(&dev->event_lock); lock(&f_owner->lock); <Interrupt> lock(&dev->event_lock);

*** DEADLOCK ***

CVSS Base Scores

version 3.1