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/perf/tests/perf-hooks.c | 49 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 tools/perf/tests/perf-hooks.c (limited to 'tools/perf/tests/perf-hooks.c') diff --git a/tools/perf/tests/perf-hooks.c b/tools/perf/tests/perf-hooks.c new file mode 100644 index 000000000..78cdeb896 --- /dev/null +++ b/tools/perf/tests/perf-hooks.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#include "tests.h" +#include "debug.h" +#include "perf-hooks.h" + +static void sigsegv_handler(int sig __maybe_unused) +{ + pr_debug("SIGSEGV is observed as expected, try to recover.\n"); + perf_hooks__recover(); + signal(SIGSEGV, SIG_DFL); + raise(SIGSEGV); + exit(-1); +} + + +static void the_hook(void *_hook_flags) +{ + int *hook_flags = _hook_flags; + + *hook_flags = 1234; + + /* Generate a segfault, test perf_hooks__recover */ + raise(SIGSEGV); +} + +static int test__perf_hooks(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int hook_flags = 0; + + signal(SIGSEGV, sigsegv_handler); + perf_hooks__set_hook("test", the_hook, &hook_flags); + perf_hooks__invoke_test(); + + /* hook is triggered? */ + if (hook_flags != 1234) { + pr_debug("Setting failed: %d (%p)\n", hook_flags, &hook_flags); + return TEST_FAIL; + } + + /* the buggy hook is removed? */ + if (perf_hooks__get_hook("test")) + return TEST_FAIL; + return TEST_OK; +} + +DEFINE_SUITE("perf hooks", perf_hooks); -- cgit v1.3.1