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, 41 insertions, 0 deletions

diff --git a/tools/perf/util/stream.h b/tools/perf/util/stream.h
new file mode 100644
index 000000000..50f7e6e04
--- /dev/null
+++ b/tools/perf/util/stream.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PERF_STREAM_H
+#define __PERF_STREAM_H
+
+struct callchain_node;
+struct evlist;
+struct evsel;
+
+struct stream {
+	struct callchain_node	*cnode;
+	struct callchain_node	*pair_cnode;
+};
+
+struct evsel_streams {
+	struct stream		*streams;
+	const struct evsel	*evsel;
+	int			nr_streams_max;
+	int			nr_streams;
+	u64			streams_hits;
+};
+
+struct evlist_streams {
+	struct evsel_streams	*ev_streams;
+	int			nr_evsel;
+};
+
+void evlist_streams__delete(struct evlist_streams *els);
+
+struct evlist_streams *evlist__create_streams(struct evlist *evlist,
+					      int nr_streams_max);
+
+struct evsel_streams *evsel_streams__entry(struct evlist_streams *els,
+					   const struct evsel *evsel);
+
+void evsel_streams__match(struct evsel_streams *es_base,
+			  struct evsel_streams *es_pair);
+
+void evsel_streams__report(struct evsel_streams *es_base,
+			   struct evsel_streams *es_pair);
+
+#endif /* __PERF_STREAM_H */