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 --- tools/testing/selftests/locking/Makefile | 10 ++++++++++ tools/testing/selftests/locking/ww_mutex.sh | 19 +++++++++++++++++++ 2 files changed, 29 insertions(+) create mode 100644 tools/testing/selftests/locking/Makefile create mode 100755 tools/testing/selftests/locking/ww_mutex.sh (limited to 'tools/testing/selftests/locking') diff --git a/tools/testing/selftests/locking/Makefile b/tools/testing/selftests/locking/Makefile new file mode 100644 index 000000000..6e7761ab3 --- /dev/null +++ b/tools/testing/selftests/locking/Makefile @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for locking/ww_mutx selftests + +# No binaries, but make sure arg-less "make" doesn't trigger "run_tests" +all: + +TEST_PROGS := ww_mutex.sh + +include ../lib.mk diff --git a/tools/testing/selftests/locking/ww_mutex.sh b/tools/testing/selftests/locking/ww_mutex.sh new file mode 100755 index 000000000..91e4ac756 --- /dev/null +++ b/tools/testing/selftests/locking/ww_mutex.sh @@ -0,0 +1,19 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +# Kselftest framework requirement - SKIP code is 4. +ksft_skip=4 + +# Runs API tests for struct ww_mutex (Wait/Wound mutexes) +if ! /sbin/modprobe -q -n test-ww_mutex; then + echo "ww_mutex: module test-ww_mutex is not found [SKIP]" + exit $ksft_skip +fi + +if /sbin/modprobe -q test-ww_mutex; then + /sbin/modprobe -q -r test-ww_mutex + echo "locking/ww_mutex: ok" +else + echo "locking/ww_mutex: [FAIL]" + exit 1 +fi -- cgit v1.3.1