CVE-2022-50555: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: tipc: fix a null-ptr-deref in tipc_topsrv_accept syzbot found a crash in tipc_topsrv_accept: KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] Workqueue: tipc_rcv tipc_topsrv_accept RIP: 0010:kernel_accept+0x22d/0x350 net/socket.c:3487 Call Trace: <TASK> tipc_topsrv_accept+0x197/0x280 net/tipc/topsrv.c:460 process_one_work+0x991/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 It was caused by srv->listener that might be set to null by tipc_topsrv_stop() in net .exit whereas it's still used in tipc_topsrv_accept() worker. srv->listener is protected by srv->idr_lock in tipc_topsrv_stop(), so add a check for srv->listener under srv->idr_lock in tipc_topsrv_accept() to avoid the null-ptr-deref. To ensure the lsock is not released during the tipc_topsrv_accept(), move sock_release() after tipc_topsrv_work_stop() where it's waiting until the tipc_topsrv_accept worker to be done. Note that sk_callback_lock is used to protect sk->sk_user_data instead of srv->listener, and it should check srv in tipc_topsrv_listener_data_ready() instead. This also ensures that no more tipc_topsrv_accept worker will be started after tipc_conn_close() is called in tipc_topsrv_stop() where it sets sk->sk_user_data to null.

Is your site exposed to CVE-2022-50555?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.17 — 4.19.264
linux	linux_kernel	4.20 — 5.4.223
linux	linux_kernel	5.5 — 5.10.153
linux	linux_kernel	5.11 — 5.15.77
linux	linux_kernel	5.16 — 6.0.7
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/24b129aed8730e48f47d852d58d76825ab6f407c https://git.kernel.org/stable/c/32a3d4660b34ce49ac0162338ebe362098e2f5df https://git.kernel.org/stable/c/7a939503fc32bff4ed60800b73ff7fbb4aea2142 https://git.kernel.org/stable/c/82cb4e4612c633a9ce320e1773114875604a3cce https://git.kernel.org/stable/c/ce69bdac2310152bb70845024d5d704c52aabfc3 https://git.kernel.org/stable/c/cedb41664e27b2cae7e21487f1bee22dcd84037d

Frequently Asked Questions

What is CVE-2022-50555? +

In the Linux kernel, the following vulnerability has been resolved: tipc: fix a null-ptr-deref in tipc_topsrv_accept syzbot found a crash in tipc_topsrv_accept: KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] Workqueue: tipc_rcv tipc_topsrv_accept RIP: 0010:kernel_accept+0x22d/0x350 net/socket.c:3487 Call Trace: <TASK> tipc_topsrv_accept+0x197/0x280 net/tipc/topsrv.c:460 process_one_work+0x991/0x1610 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 It was caused by srv->listener that might be set to null by tipc_topsrv_stop() in net .exit whereas it's still used in tipc_topsrv_accept() worker. srv->listener is protected by srv->idr_lock in tipc_topsrv_stop(), so add a check for srv->listener under srv->idr_lock in tipc_topsrv_accept() to avoid the null-ptr-deref. To ensure the lsock is not released during the tipc_topsrv_accept(), move sock_release() after tipc_topsrv_work_stop() where it's waiting until the tipc_topsrv_accept worker to be done. Note that sk_callback_lock is used to protect sk->sk_user_data instead of srv->listener, and it should check srv in tipc_topsrv_listener_data_ready() instead. This also ensures that no more tipc_topsrv_accept worker will be started after tipc_conn_close() is called in tipc_topsrv_stop() where it sets sk->sk_user_data to null. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2022-50555? +

CVE-2022-50555 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2022-50555? +

CVE-2022-50555 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2022-50555? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-8479

IEC 60870-5-104 used in bidirectional mode in RTU500 is vulnerable for a NULL pointer dereferencing, if a specially crafted sequence …

CVE-2025-24031

PAM-PKCS#11 is a Linux-PAM login module that allows a X.509 certificate based user login. In versions 0.6.12 and prior, the …

CVE-2025-31115

XZ Utils provide a general-purpose data-compression library plus command-line tools. In XZ Utils 5.3.3alpha to 5.8.0, the multithreaded .xz decoder …

CVE-2025-0121

A null pointer dereference vulnerability in the Palo Alto Networks Cortex® XDR agent on Windows devices allows a low-privileged local …

CVE-2023-45925

GNU Midnight Commander 4.8.29-146-g299d9a2fb was discovered to contain a NULL pointer dereference via the function x_error_handler() at tty/x11conn.c. NOTE: this …

CVE-2025-6398

A null pointer dereference vulnerability exists in the IOMap64.sys driver of ASUS AI Suite 3. The vulnerability can be triggered …

CVE-2022-50555