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, 134 insertions, 0 deletions

diff --git a/tools/perf/tests/subcmd-help.c b/tools/perf/tests/subcmd-help.c
new file mode 100644
index 000000000..9da96a16f
--- /dev/null
+++ b/tools/perf/tests/subcmd-help.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "tests.h"
+#include <linux/compiler.h>
+#include <subcmd/help.h>
+
+static int test__load_cmdnames(struct test_suite *test __maybe_unused,
+			       int subtest __maybe_unused)
+{
+	struct cmdnames cmds = {};
+
+	add_cmdname(&cmds, "aaa", 3);
+	add_cmdname(&cmds, "foo", 3);
+	add_cmdname(&cmds, "xyz", 3);
+
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds, "aaa") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds, "bar") == 0);
+	TEST_ASSERT_VAL("case sensitive", is_in_cmdlist(&cmds, "XYZ") == 0);
+
+	clean_cmdnames(&cmds);
+	return TEST_OK;
+}
+
+static int test__uniq_cmdnames(struct test_suite *test __maybe_unused,
+			       int subtest __maybe_unused)
+{
+	struct cmdnames cmds = {};
+
+	/* uniq() assumes it's sorted */
+	add_cmdname(&cmds, "aaa", 3);
+	add_cmdname(&cmds, "aaa", 3);
+	add_cmdname(&cmds, "bbb", 3);
+
+	TEST_ASSERT_VAL("invalid original size", cmds.cnt == 3);
+	/* uniquify command names (to remove second 'aaa') */
+	uniq(&cmds);
+	TEST_ASSERT_VAL("invalid final size", cmds.cnt == 2);
+
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds, "aaa") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds, "bbb") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds, "ccc") == 0);
+
+	clean_cmdnames(&cmds);
+	return TEST_OK;
+}
+
+static int test__exclude_cmdnames(struct test_suite *test __maybe_unused,
+				  int subtest __maybe_unused)
+{
+	struct cmdnames cmds1 = {};
+	struct cmdnames cmds2 = {};
+
+	add_cmdname(&cmds1, "aaa", 3);
+	add_cmdname(&cmds1, "bbb", 3);
+	add_cmdname(&cmds1, "ccc", 3);
+	add_cmdname(&cmds1, "ddd", 3);
+	add_cmdname(&cmds1, "eee", 3);
+	add_cmdname(&cmds1, "fff", 3);
+	add_cmdname(&cmds1, "ggg", 3);
+	add_cmdname(&cmds1, "hhh", 3);
+	add_cmdname(&cmds1, "iii", 3);
+	add_cmdname(&cmds1, "jjj", 3);
+
+	add_cmdname(&cmds2, "bbb", 3);
+	add_cmdname(&cmds2, "eee", 3);
+	add_cmdname(&cmds2, "jjj", 3);
+
+	TEST_ASSERT_VAL("invalid original size", cmds1.cnt == 10);
+	TEST_ASSERT_VAL("invalid original size", cmds2.cnt == 3);
+
+	/* remove duplicate command names in cmds1 */
+	exclude_cmds(&cmds1, &cmds2);
+
+	TEST_ASSERT_VAL("invalid excluded size", cmds1.cnt == 7);
+	TEST_ASSERT_VAL("invalid excluded size", cmds2.cnt == 3);
+
+	/* excluded commands should not belong to cmds1 */
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "aaa") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "bbb") == 0);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "ccc") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "ddd") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "eee") == 0);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "fff") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "ggg") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "hhh") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "iii") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "jjj") == 0);
+
+	/* they should be only in cmds2 */
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds2, "bbb") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds2, "eee") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds2, "jjj") == 1);
+
+	clean_cmdnames(&cmds1);
+	clean_cmdnames(&cmds2);
+	return TEST_OK;
+}
+
+static int test__exclude_cmdnames_no_overlap(struct test_suite *test __maybe_unused,
+					     int subtest __maybe_unused)
+{
+	struct cmdnames cmds1 = {};
+	struct cmdnames cmds2 = {};
+
+	add_cmdname(&cmds1, "read-vdso32", 11);
+	add_cmdname(&cmds2, "archive", 7);
+
+	TEST_ASSERT_VAL("invalid original size", cmds1.cnt == 1);
+	TEST_ASSERT_VAL("invalid original size", cmds2.cnt == 1);
+
+	exclude_cmds(&cmds1, &cmds2);
+
+	TEST_ASSERT_VAL("invalid excluded size", cmds1.cnt == 1);
+	TEST_ASSERT_VAL("invalid excluded size", cmds2.cnt == 1);
+
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "read-vdso32") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "archive") == 0);
+
+	clean_cmdnames(&cmds1);
+	clean_cmdnames(&cmds2);
+	return TEST_OK;
+}
+
+static struct test_case tests__subcmd_help[] = {
+	TEST_CASE("Load subcmd names", load_cmdnames),
+	TEST_CASE("Uniquify subcmd names", uniq_cmdnames),
+	TEST_CASE("Exclude duplicate subcmd names", exclude_cmdnames),
+	TEST_CASE("Exclude disjoint subcmd names", exclude_cmdnames_no_overlap),
+	{	.name = NULL, }
+};
+
+struct test_suite suite__subcmd_help = {
+	.desc = "libsubcmd help tests",
+	.test_cases = tests__subcmd_help,
+};