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-ec | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 Documentation/ABI/testing/debugfs-ec (limited to 'Documentation/ABI/testing/debugfs-ec') diff --git a/Documentation/ABI/testing/debugfs-ec b/Documentation/ABI/testing/debugfs-ec new file mode 100644 index 000000000..ab6099daa --- /dev/null +++ b/Documentation/ABI/testing/debugfs-ec @@ -0,0 +1,21 @@ +What: /sys/kernel/debug/ec/*/{gpe,use_global_lock,io} +Date: July 2010 +Contact: Thomas Renninger +Description: + +General information like which GPE is assigned to the EC and whether +the global lock should get used. +Knowing the EC GPE one can watch the amount of HW events related to +the EC here (XY -> GPE number from `/sys/kernel/debug/ec/*/gpe`): +/sys/firmware/acpi/interrupts/gpeXY + +The io file is binary and a userspace tool located here: +ftp://ftp.suse.com/pub/people/trenn/sources/ec/ +should get used to read out the 256 Embedded Controller registers +or writing to them. + +CAUTION: + Do not write to the Embedded Controller if you don't know + what you are doing! Rebooting afterwards also is a good idea. + This can influence the way your machine is cooled and fans may + not get switched on again after you did a wrong write. -- cgit v1.3.1