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/gpio-cdev | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 Documentation/ABI/testing/gpio-cdev (limited to 'Documentation/ABI/testing/gpio-cdev') diff --git a/Documentation/ABI/testing/gpio-cdev b/Documentation/ABI/testing/gpio-cdev new file mode 100644 index 000000000..c9689b2a6 --- /dev/null +++ b/Documentation/ABI/testing/gpio-cdev @@ -0,0 +1,28 @@ +What: /dev/gpiochip[0-9]+ +Date: November 2015 +KernelVersion: 4.4 +Contact: linux-gpio@vger.kernel.org +Description: + The character device files /dev/gpiochip* are the interface + between GPIO chips and userspace. + + The ioctl(2)-based ABI is defined in + [include/uapi] and documented in + Documentation/userspace-api/gpio/chardev.rst. + + The following file operations are supported: + + open(2) + Currently the only useful flags are O_RDWR. + + ioctl(2) + Initiate various actions. + + See Documentation/userspace-api/gpio/chardev.rst + for a description of all ioctls. + + close(2) + Stops and free up the I/O contexts that was associated + with the file descriptor. + +Users: TBD -- cgit v1.3.1