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, 51 insertions, 0 deletions

diff --git a/tools/perf/util/time-utils.h b/tools/perf/util/time-utils.h
new file mode 100644
index 000000000..1142b0bdd
--- /dev/null
+++ b/tools/perf/util/time-utils.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TIME_UTILS_H_
+#define _TIME_UTILS_H_
+
+#include <stddef.h>
+#include <time.h>
+#include <linux/types.h>
+
+struct perf_time_interval {
+	u64 start, end;
+};
+
+int parse_nsec_time(const char *str, u64 *ptime);
+
+int perf_time__parse_str(struct perf_time_interval *ptime, const char *ostr);
+
+int perf_time__percent_parse_str(struct perf_time_interval *ptime_buf, int num,
+				 const char *ostr, u64 start, u64 end);
+
+struct perf_time_interval *perf_time__range_alloc(const char *ostr, int *size);
+
+bool perf_time__skip_sample(struct perf_time_interval *ptime, u64 timestamp);
+
+bool perf_time__ranges_skip_sample(struct perf_time_interval *ptime_buf,
+				   int num, u64 timestamp);
+
+struct perf_session;
+
+int perf_time__parse_for_ranges_reltime(const char *str, struct perf_session *session,
+				struct perf_time_interval **ranges,
+				int *range_size, int *range_num,
+				bool reltime);
+
+int perf_time__parse_for_ranges(const char *str, struct perf_session *session,
+				struct perf_time_interval **ranges,
+				int *range_size, int *range_num);
+
+int timestamp__scnprintf_usec(u64 timestamp, char *buf, size_t sz);
+int timestamp__scnprintf_nsec(u64 timestamp, char *buf, size_t sz);
+
+int fetch_current_timestamp(char *buf, size_t sz);
+
+static inline unsigned long long rdclock(void)
+{
+	struct timespec ts;
+
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
+}
+
+#endif