CVE-2022-40476

What it actually does

Null pointer dereference in fs/io_uring.c causes kernel panic when a local process performs specific io_uring operations.

Why it matters to the business

Local users or processes can trigger system crashes, leading to unplanned downtime and loss of availability on affected Linux systems.

How an attack unfolds

An attacker with local access crafts io_uring submission queue entries that reach the vulnerable code path, dereferencing a null pointer and forcing a kernel oops or panic.

How to fix it

Upgrade the Linux kernel to version 5.15.62 or newer; rebuild and reboot with the patched kernel; apply vendor backports if a distribution-specific update is available.

How to confirm the fix worked

Confirm kernel version is at least 5.15.62; attempt reproduction of the null dereference with a minimal io_uring reproducer in a test environment; monitor for absence of panic messages referencing io_uring.c.

Typical attack path

1. Obtain local shell or process execution on target host
2. Load or invoke io_uring syscalls with crafted ring parameters
3. Trigger the null dereference in the kernel io_uring handler
4. Observe kernel crash and system reboot or halt

How to detect it

Search kernel logs for oops or panic messages containing io_uring and null pointer dereference; review audit logs for unusual io_uring syscall patterns from non-root processes.

What your security team should do

• Prioritize kernel updates on all systems exposing io_uring to untrusted local users
• Restrict unprivileged use of io_uring via seccomp or kernel boot parameters where feasible
• Monitor vendor security advisories for distribution-specific backports