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-devices-removable | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-devices-removable (limited to 'Documentation/ABI/testing/sysfs-devices-removable') diff --git a/Documentation/ABI/testing/sysfs-devices-removable b/Documentation/ABI/testing/sysfs-devices-removable new file mode 100644 index 000000000..754ecb458 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-removable @@ -0,0 +1,20 @@ +What: /sys/devices/.../removable +Date: May 2021 +Contact: Rajat Jain +Description: + Information about whether a given device can be removed from the + platform by the user. This is determined by its subsystem in a + bus / platform-specific way. This attribute is only present for + devices that can support determining such information: + + =========== =================================================== + "removable" device can be removed from the platform by the user + "fixed" device is fixed to the platform / cannot be removed + by the user. + "unknown" The information is unavailable / cannot be deduced. + =========== =================================================== + + Currently this is only supported by USB (which infers the + information from a combination of hub descriptor bits and + platform-specific data such as ACPI) and PCI (which gets this + from ACPI / device tree). -- cgit v1.3.1