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, 44 insertions, 0 deletions

diff --git a/tools/perf/tests/demangle-ocaml-test.c b/tools/perf/tests/demangle-ocaml-test.c
new file mode 100644
index 000000000..612c788b7
--- /dev/null
+++ b/tools/perf/tests/demangle-ocaml-test.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "debug.h"
+#include "symbol.h"
+#include "tests.h"
+
+static int test__demangle_ocaml(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
+{
+	int ret = TEST_OK;
+	char *buf = NULL;
+	size_t i;
+
+	struct {
+		const char *mangled, *demangled;
+	} test_cases[] = {
+		{ "main",
+		  NULL },
+		{ "camlStdlib__array__map_154",
+		  "Stdlib.array.map_154" },
+		{ "camlStdlib__anon_fn$5bstdlib$2eml$3a334$2c0$2d$2d54$5d_1453",
+		  "Stdlib.anon_fn[stdlib.ml:334,0--54]_1453" },
+		{ "camlStdlib__bytes__$2b$2b_2205",
+		  "Stdlib.bytes.++_2205" },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(test_cases); i++) {
+		buf = dso__demangle_sym(/*dso=*/NULL, /*kmodule=*/0, test_cases[i].mangled);
+		if ((buf == NULL && test_cases[i].demangled != NULL)
+				|| (buf != NULL && test_cases[i].demangled == NULL)
+				|| (buf != NULL && strcmp(buf, test_cases[i].demangled))) {
+			pr_debug("FAILED: %s: %s != %s\n", test_cases[i].mangled,
+				 buf == NULL ? "(null)" : buf,
+				 test_cases[i].demangled == NULL ? "(null)" : test_cases[i].demangled);
+			ret = TEST_FAIL;
+		}
+		free(buf);
+	}
+
+	return ret;
+}
+
+DEFINE_SUITE("Demangle OCaml", demangle_ocaml);