From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: 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] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- Documentation/ABI/testing/sysfs-bus-mcb | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-mcb (limited to 'Documentation/ABI/testing/sysfs-bus-mcb') diff --git a/Documentation/ABI/testing/sysfs-bus-mcb b/Documentation/ABI/testing/sysfs-bus-mcb new file mode 100644 index 000000000..77947c509 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-mcb @@ -0,0 +1,29 @@ +What: /sys/bus/mcb/devices/mcb:X +Date: March 2016 +KernelVersion: 4.7 +Contact: Johannes Thumshirn +Description: Hardware chip or device hosting the MEN chameleon bus + +What: /sys/bus/mcb/devices/mcb:X/revision +Date: March 2016 +KernelVersion: 4.7 +Contact: Johannes Thumshirn +Description: The FPGA's revision number + +What: /sys/bus/mcb/devices/mcb:X/minor +Date: March 2016 +KernelVersion: 4.7 +Contact: Johannes Thumshirn +Description: The FPGA's minor number + +What: /sys/bus/mcb/devices/mcb:X/model +Date: March 2016 +KernelVersion: 4.7 +Contact: Johannes Thumshirn +Description: The FPGA's model number + +What: /sys/bus/mcb/devices/mcb:X/name +Date: March 2016 +KernelVersion: 4.7 +Contact: Johannes Thumshirn +Description: The FPGA's name -- cgit v1.3.1