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 | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-devices (limited to 'Documentation/ABI/testing/sysfs-devices') diff --git a/Documentation/ABI/testing/sysfs-devices b/Documentation/ABI/testing/sysfs-devices new file mode 100644 index 000000000..5fcc94358 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices @@ -0,0 +1,25 @@ +What: /sys/devices +Date: February 2006 +Contact: Greg Kroah-Hartman +Description: + The /sys/devices tree contains a snapshot of the + internal state of the kernel device tree. Devices will + be added and removed dynamically as the machine runs, + and between different kernel versions, the layout of the + devices within this tree will change. + + Please do not rely on the format of this tree because of + this. If a program wishes to find different things in + the tree, please use the /sys/class structure and rely + on the symlinks there to point to the proper location + within the /sys/devices tree of the individual devices. + Or rely on the uevent messages to notify programs of + devices being added and removed from this tree to find + the location of those devices. + + Note that sometimes not all devices along the directory + chain will have emitted uevent messages, so userspace + programs must be able to handle such occurrences. + +Users: + udev -- cgit v1.3.1