CVE-2026-89489openrisc: fix arbitrary kernel memory access via or1k_atomic syscall

Official 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. [shorne@gmail.com: fix comment style]

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/bf310718c6fa6adeee06d207a55489546d860e2c
• https://git.kernel.org/stable/c/497cba0b02e5555d99fe9ee1dc478af743ab7f7a
• https://git.kernel.org/stable/c/1f2e92e499d863f81df1732af59b4a3559969193
• https://git.kernel.org/stable/c/574ae2ac2b314aa33498cd2c28add106cbe644f2
• https://git.kernel.org/stable/c/a520e8cac54fb403f3800125b606f55fcad42cb9
• https://git.kernel.org/stable/c/d64a75369cd0f2ee79afcc9d9ca34a3890989379
• https://git.kernel.org/stable/c/b53435c079c78f89f70a62dd5a322cca4e292b34
• https://git.kernel.org/stable/c/78004e9a87f240df03e2f73120d291763c32e0a7