GHSA-9h35-hqff-9v3w

Опубликовано: 24 июн. 2026

Источник: github

Github: Не прошло ревью

CVSS3: 7.5

Описание

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:

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

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:

CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait().
CPU 1 (process context) attempts write_lock(&tasklist_lock) in fork() or exit() and spins, which blocks all new readers.
CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception).
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); lock(&dev->event_lock);

*** DEADLOCK ***

Ссылки

EPSS

Процентиль: 37%

0.00455

Низкий

7.5 High

CVSS3

CVE ID

CVE-2026-52946

Дефекты

CWE-667

Связанные уязвимости

CVE-2026-52946

CVSS3: 7.5

ubuntu

около 1 месяца назад

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), ...