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, 43 insertions, 0 deletions

diff --git a/tools/perf/util/pmus.h b/tools/perf/util/pmus.h
new file mode 100644
index 000000000..0d55edb3f
--- /dev/null
+++ b/tools/perf/util/pmus.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PMUS_H
+#define __PMUS_H
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct perf_event_attr;
+struct perf_pmu;
+struct print_callbacks;
+
+size_t pmu_name_len_no_suffix(const char *str);
+/* Exposed for testing only. */
+int pmu_name_cmp(const char *lhs_pmu_name, const char *rhs_pmu_name);
+
+void perf_pmus__destroy(void);
+
+struct perf_pmu *perf_pmus__find(const char *name);
+struct perf_pmu *perf_pmus__find_by_type(unsigned int type);
+struct perf_pmu *perf_pmus__find_by_attr(const struct perf_event_attr *attr);
+
+struct perf_pmu *perf_pmus__scan(struct perf_pmu *pmu);
+struct perf_pmu *perf_pmus__scan_core(struct perf_pmu *pmu);
+struct perf_pmu *perf_pmus__scan_for_event(struct perf_pmu *pmu, const char *event);
+struct perf_pmu *perf_pmus__scan_matching_wildcard(struct perf_pmu *pmu, const char *wildcard);
+struct perf_pmu *perf_pmus__scan_for_uncore_id(struct perf_pmu *pmu, const char *compat);
+
+const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str);
+
+void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *print_state);
+void perf_pmus__print_raw_pmu_events(const struct print_callbacks *print_cb, void *print_state);
+bool perf_pmus__have_event(const char *pname, const char *name);
+int perf_pmus__num_core_pmus(void);
+bool perf_pmus__supports_extended_type(void);
+
+struct perf_pmu *perf_pmus__add_test_pmu(int test_sysfs_dirfd, const char *name);
+struct perf_pmu *perf_pmus__add_test_hwmon_pmu(const char *hwmon_dir,
+					       const char *sysfs_name,
+					       const char *name);
+struct perf_pmu *perf_pmus__fake_pmu(void);
+struct perf_pmu *perf_pmus__find_core_pmu(void);
+
+#endif /* __PMUS_H */