CVE-2026-89489

/// Technical description

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

openrisc: fix arbitrary kernel memory access via or1k_atomic syscall

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user

pointers, v1 and v2, and swaps the words they point to in hand-written

assembly.

l.lwz r29,0(r4)

l.lwz r27,0(r5)

l.sw 0(r4),r27

l.sw 0(r5),r29

The pointers are not checked with access_ok(). The four memory

accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall

reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It

overwrites kernel data such as the sys_call_table, gaining code

execution in kernel context.

Check both pointers before entering the critical section. Add fixups

for the four memory accesses so faults on valid but unmapped user

addresses return -EFAULT.

[[email protected]: fix comment style]

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References