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/ppc-memtrace | 46 ++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/ABI/testing/ppc-memtrace (limited to 'Documentation/ABI/testing/ppc-memtrace') diff --git a/Documentation/ABI/testing/ppc-memtrace b/Documentation/ABI/testing/ppc-memtrace new file mode 100644 index 000000000..9606aed33 --- /dev/null +++ b/Documentation/ABI/testing/ppc-memtrace @@ -0,0 +1,46 @@ +What: /sys/kernel/debug/powerpc/memtrace +Date: Aug 2017 +KernelVersion: 4.14 +Contact: linuxppc-dev@lists.ozlabs.org +Description: This folder contains the relevant debugfs files for the + hardware trace macro to use. CONFIG_PPC64_HARDWARE_TRACING + must be set. + +What: /sys/kernel/debug/powerpc/memtrace/enable +Date: Aug 2017 +KernelVersion: 4.14 +Contact: linuxppc-dev@lists.ozlabs.org +Description: Write an integer containing the size in bytes of the memory + you want removed from each NUMA node to this file - it must be + aligned to the memblock size. This amount of RAM will be removed + from each NUMA node in the kernel mappings and the following + debugfs files will be created. Once memory is successfully + removed from each node, the following files are created. To + re-add memory to the kernel, echo 0 into this file (it will be + automatically onlined). + +What: /sys/kernel/debug/powerpc/memtrace/ +Date: Aug 2017 +KernelVersion: 4.14 +Contact: linuxppc-dev@lists.ozlabs.org +Description: This directory contains information about the removed memory + from the specific NUMA node. + +What: /sys/kernel/debug/powerpc/memtrace//size +Date: Aug 2017 +KernelVersion: 4.14 +Contact: linuxppc-dev@lists.ozlabs.org +Description: This contains the size of the memory removed from the node. + +What: /sys/kernel/debug/powerpc/memtrace//start +Date: Aug 2017 +KernelVersion: 4.14 +Contact: linuxppc-dev@lists.ozlabs.org +Description: This contains the start address of the removed memory. + +What: /sys/kernel/debug/powerpc/memtrace//trace +Date: Aug 2017 +KernelVersion: 4.14 +Contact: linuxppc-dev@lists.ozlabs.org +Description: This is where the hardware trace macro will output the trace + it generates. -- cgit v1.3.1