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/debugfs-moxtet | 35 ++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 Documentation/ABI/testing/debugfs-moxtet (limited to 'Documentation/ABI/testing/debugfs-moxtet') diff --git a/Documentation/ABI/testing/debugfs-moxtet b/Documentation/ABI/testing/debugfs-moxtet new file mode 100644 index 000000000..637d8587d --- /dev/null +++ b/Documentation/ABI/testing/debugfs-moxtet @@ -0,0 +1,35 @@ +What: /sys/kernel/debug/moxtet/input +Date: March 2019 +KernelVersion: 5.3 +Contact: Marek Behún +Description: (Read) Read input from the shift registers, in hexadecimal. + Returns N+1 bytes, where N is the number of Moxtet connected + modules. The first byte is from the CPU board itself. + + Example:: + + 101214 + + == ======================================= + 10 CPU board with SD card + 12 2 = PCIe module, 1 = IRQ not active + 14 4 = Peridot module, 1 = IRQ not active + == ======================================= + +What: /sys/kernel/debug/moxtet/output +Date: March 2019 +KernelVersion: 5.3 +Contact: Marek Behún +Description: (RW) Read last written value to the shift registers, in + hexadecimal, or write values to the shift registers, also + in hexadecimal. + + Example:: + + 0102 + + == ================================================ + 01 01 was last written, or is to be written, to the + first module's shift register + 02 the same for second module + == ================================================ -- cgit v1.3.1