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]
Attack Parameters
Impact Assessment
CVSS Vector v3.1