openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

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 <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 152 insertions, 0 deletions

diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c
new file mode 100644
index 000000000..b6e469753
--- /dev/null
+++ b/tools/perf/tests/sw-clock.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <linux/compiler.h>
+#include <linux/string.h>
+
+#include "tests.h"
+#include "util/debug.h"
+#include "util/evsel.h"
+#include "util/evlist.h"
+#include "util/cpumap.h"
+#include "util/mmap.h"
+#include "util/sample.h"
+#include "util/thread_map.h"
+#include <perf/evlist.h>
+#include <perf/mmap.h>
+
+#define NR_LOOPS  10000000
+
+/*
+ * This test will open software clock events (cpu-clock, task-clock)
+ * then check their frequency -> period conversion has no artifact of
+ * setting period to 1 forcefully.
+ */
+static int __test__sw_clock_freq(enum perf_sw_ids clock_id)
+{
+	int i, err = -1;
+	volatile int tmp __maybe_unused = 0;
+	u64 total_periods = 0;
+	int nr_samples = 0;
+	char sbuf[STRERR_BUFSIZE];
+	union perf_event *event;
+	struct evsel *evsel;
+	struct evlist *evlist;
+	struct perf_event_attr attr = {
+		.type = PERF_TYPE_SOFTWARE,
+		.config = clock_id,
+		.sample_type = PERF_SAMPLE_PERIOD,
+		.exclude_kernel = 1,
+		.disabled = 1,
+		.freq = 1,
+	};
+	struct perf_cpu_map *cpus = NULL;
+	struct perf_thread_map *threads = NULL;
+	struct mmap *md;
+
+	attr.sample_freq = 500;
+
+	evlist = evlist__new();
+	if (evlist == NULL) {
+		pr_debug("evlist__new\n");
+		return -1;
+	}
+
+	evsel = evsel__new(&attr);
+	if (evsel == NULL) {
+		pr_debug("evsel__new\n");
+		goto out_delete_evlist;
+	}
+	evlist__add(evlist, evsel);
+
+	cpus = perf_cpu_map__new_any_cpu();
+	threads = thread_map__new_by_tid(getpid());
+	if (!cpus || !threads) {
+		err = -ENOMEM;
+		pr_debug("Not enough memory to create thread/cpu maps\n");
+		goto out_delete_evlist;
+	}
+
+	perf_evlist__set_maps(&evlist->core, cpus, threads);
+
+	if (evlist__open(evlist)) {
+		const char *knob = "/proc/sys/kernel/perf_event_max_sample_rate";
+
+		err = -errno;
+		pr_debug("Couldn't open evlist: %s\nHint: check %s, using %" PRIu64 " in this test.\n",
+			 str_error_r(errno, sbuf, sizeof(sbuf)),
+			 knob, (u64)attr.sample_freq);
+		goto out_delete_evlist;
+	}
+
+	err = evlist__mmap(evlist, 128);
+	if (err < 0) {
+		pr_debug("failed to mmap event: %d (%s)\n", errno,
+			 str_error_r(errno, sbuf, sizeof(sbuf)));
+		goto out_delete_evlist;
+	}
+
+	evlist__enable(evlist);
+
+	/* collect samples */
+	for (i = 0; i < NR_LOOPS; i++)
+		tmp++;
+
+	evlist__disable(evlist);
+
+	md = &evlist->mmap[0];
+	if (perf_mmap__read_init(&md->core) < 0)
+		goto out_init;
+
+	while ((event = perf_mmap__read_event(&md->core)) != NULL) {
+		struct perf_sample sample;
+
+		perf_sample__init(&sample, /*all=*/false);
+		if (event->header.type != PERF_RECORD_SAMPLE)
+			goto next_event;
+
+		err = evlist__parse_sample(evlist, event, &sample);
+		if (err < 0) {
+			pr_debug("Error during parse sample\n");
+			perf_sample__exit(&sample);
+			goto out_delete_evlist;
+		}
+
+		total_periods += sample.period;
+		nr_samples++;
+next_event:
+		perf_mmap__consume(&md->core);
+		perf_sample__exit(&sample);
+	}
+	perf_mmap__read_done(&md->core);
+
+out_init:
+	if ((u64) nr_samples == total_periods) {
+		pr_debug("All (%d) samples have period value of 1!\n",
+			 nr_samples);
+		err = -1;
+	}
+
+out_delete_evlist:
+	perf_cpu_map__put(cpus);
+	perf_thread_map__put(threads);
+	evlist__delete(evlist);
+	return err;
+}
+
+static int test__sw_clock_freq(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
+{
+	int ret;
+
+	ret = __test__sw_clock_freq(PERF_COUNT_SW_CPU_CLOCK);
+	if (!ret)
+		ret = __test__sw_clock_freq(PERF_COUNT_SW_TASK_CLOCK);
+
+	return ret;
+}
+
+DEFINE_SUITE("Software clock events period values", sw_clock_freq);