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/admin-guide/sysctl/abi.rst | 34 ++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 Documentation/admin-guide/sysctl/abi.rst (limited to 'Documentation/admin-guide/sysctl/abi.rst') diff --git a/Documentation/admin-guide/sysctl/abi.rst b/Documentation/admin-guide/sysctl/abi.rst new file mode 100644 index 000000000..4e6db0a2a --- /dev/null +++ b/Documentation/admin-guide/sysctl/abi.rst @@ -0,0 +1,34 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +================================ +Documentation for /proc/sys/abi/ +================================ + +.. See scripts/check-sysctl-docs to keep this up to date: +.. scripts/check-sysctl-docs -vtable="abi" \ +.. Documentation/admin-guide/sysctl/abi.rst \ +.. $(git grep -l register_sysctl_) + +Copyright (c) 2020, Stephen Kitt + +For general info, see Documentation/admin-guide/sysctl/index.rst. + +------------------------------------------------------------------------------ + +The files in ``/proc/sys/abi`` can be used to see and modify +ABI-related settings. + +Currently, these files might (depending on your configuration) +show up in ``/proc/sys/kernel``: + +.. contents:: :local: + +vsyscall32 (x86) +================ + +Determines whether the kernels maps a vDSO page into 32-bit processes; +can be set to 1 to enable, or 0 to disable. Defaults to enabled if +``CONFIG_COMPAT_VDSO`` is set, disabled otherwise. + +This controls the same setting as the ``vdso32`` kernel boot +parameter. -- cgit v1.3.1