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 ***
References
Configurations
Configuration 1 (hide)
|
History
14 Jul 2026, 16:58
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/00633c4683828acd5256fa8d5163f440d74bbe71 - Patch | |
| References | () https://git.kernel.org/stable/c/1bee417678f1135e35b25a37734db46aa94258d2 - Patch | |
| References | () https://git.kernel.org/stable/c/20a93e397abe850c49b6fa0e8cc827b5f634a8f5 - Patch | |
| References | () https://git.kernel.org/stable/c/32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33 - Patch | |
| References | () https://git.kernel.org/stable/c/36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed - Patch | |
| References | () https://git.kernel.org/stable/c/54626335ea4174ab2d9a183b511d825f6765e47b - Patch | |
| References | () https://git.kernel.org/stable/c/897d6a7247739fb1528f98c575df4f2e5de7f994 - Patch | |
| References | () https://git.kernel.org/stable/c/b5fa9e32fb6718f70c986ee14dd5d01b4846f331 - Patch | |
| References | () https://git.kernel.org/stable/c/bfcc8e8d8a495bb34cae9e620adfb75fb13a3954 - Patch | |
| CWE | CWE-667 | |
| First Time |
Linux linux Kernel
Linux |
|
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:* |
29 Jun 2026, 06:16
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
28 Jun 2026, 08:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 7.5 |
24 Jun 2026, 17:17
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-06-24 17:17
Updated : 2026-07-14 16:58
NVD link : CVE-2026-52946
Mitre link : CVE-2026-52946
CVE.ORG link : CVE-2026-52946
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-667
Improper Locking