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-class-stm | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-class-stm (limited to 'Documentation/ABI/testing/sysfs-class-stm') diff --git a/Documentation/ABI/testing/sysfs-class-stm b/Documentation/ABI/testing/sysfs-class-stm new file mode 100644 index 000000000..77ed3da0f --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-stm @@ -0,0 +1,24 @@ +What: /sys/class/stm//masters +Date: June 2015 +KernelVersion: 4.3 +Contact: Alexander Shishkin +Description: + Shows first and last available to software master numbers on + this STM device. + +What: /sys/class/stm//channels +Date: June 2015 +KernelVersion: 4.3 +Contact: Alexander Shishkin +Description: + Shows the number of channels per master on this STM device. + +What: /sys/class/stm//hw_override +Date: March 2016 +KernelVersion: 4.7 +Contact: Alexander Shishkin +Description: + Reads as 0 if master numbers in the STP stream produced by + this stm device will match the master numbers assigned by + the software or 1 if the stm hardware overrides software + assigned masters. -- cgit v1.3.1