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 --- .../devicetree/bindings/pmem/pmem-region.yaml | 48 ++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 Documentation/devicetree/bindings/pmem/pmem-region.yaml (limited to 'Documentation/devicetree/bindings/pmem') diff --git a/Documentation/devicetree/bindings/pmem/pmem-region.yaml b/Documentation/devicetree/bindings/pmem/pmem-region.yaml new file mode 100644 index 000000000..bd0f0c793 --- /dev/null +++ b/Documentation/devicetree/bindings/pmem/pmem-region.yaml @@ -0,0 +1,48 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/pmem-region.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +maintainers: + - Oliver O'Halloran + +title: Persistent Memory Regions + +description: | + Persistent memory refers to a class of memory devices that are: + + a) Usable as main system memory (i.e. cacheable), and + b) Retain their contents across power failure. + + Given b) it is best to think of persistent memory as a kind of memory mapped + storage device. To ensure data integrity the operating system needs to manage + persistent regions separately to the normal memory pool. To aid with that this + binding provides a standardised interface for discovering where persistent + memory regions exist inside the physical address space. + +properties: + compatible: + const: pmem-region + + reg: + maxItems: 1 + + volatile: + description: + Indicates the region is volatile (non-persistent) and the OS can skip + cache flushes for writes + type: boolean + +required: + - compatible + - reg + +additionalProperties: false + +examples: + - | + pmem@5000 { + compatible = "pmem-region"; + reg = <0x00005000 0x00001000>; + }; -- cgit v1.3.1