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, 91 insertions, 0 deletions

diff --git a/tools/perf/util/compress.h b/tools/perf/util/compress.h
new file mode 100644
index 000000000..6cfecfca1
--- /dev/null
+++ b/tools/perf/util/compress.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef PERF_COMPRESS_H
+#define PERF_COMPRESS_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <linux/compiler.h>
+#ifdef HAVE_ZSTD_SUPPORT
+#include <zstd.h>
+#endif
+
+#ifdef HAVE_ZLIB_SUPPORT
+int gzip_decompress_to_file(const char *input, int output_fd);
+bool gzip_is_compressed(const char *input);
+#endif
+
+#ifdef HAVE_LZMA_SUPPORT
+int lzma_decompress_stream_to_file(FILE *input, int output_fd);
+int lzma_decompress_to_file(const char *input, int output_fd);
+bool lzma_is_compressed(const char *input);
+#else
+static inline
+int lzma_decompress_stream_to_file(FILE *input __maybe_unused,
+				   int output_fd __maybe_unused)
+{
+	return -1;
+}
+static inline
+int lzma_decompress_to_file(const char *input __maybe_unused,
+			    int output_fd __maybe_unused)
+{
+	return -1;
+}
+static inline int lzma_is_compressed(const char *input __maybe_unused)
+{
+	return false;
+}
+#endif
+
+struct zstd_data {
+#ifdef HAVE_ZSTD_SUPPORT
+	ZSTD_CStream	*cstream;
+	ZSTD_DStream	*dstream;
+	int comp_level;
+#endif
+};
+
+#ifdef HAVE_ZSTD_SUPPORT
+
+int zstd_init(struct zstd_data *data, int level);
+int zstd_fini(struct zstd_data *data);
+
+ssize_t zstd_compress_stream_to_records(struct zstd_data *data, void *dst, size_t dst_size,
+				       void *src, size_t src_size, size_t max_record_size,
+				       size_t process_header(void *record, size_t increment));
+
+size_t zstd_decompress_stream(struct zstd_data *data, void *src, size_t src_size,
+			      void *dst, size_t dst_size);
+#else /* !HAVE_ZSTD_SUPPORT */
+
+static inline int zstd_init(struct zstd_data *data __maybe_unused, int level __maybe_unused)
+{
+	return 0;
+}
+
+static inline int zstd_fini(struct zstd_data *data __maybe_unused)
+{
+	return 0;
+}
+
+static inline
+ssize_t zstd_compress_stream_to_records(struct zstd_data *data __maybe_unused,
+				       void *dst __maybe_unused, size_t dst_size __maybe_unused,
+				       void *src __maybe_unused, size_t src_size __maybe_unused,
+				       size_t max_record_size __maybe_unused,
+				       size_t process_header(void *record, size_t increment) __maybe_unused)
+{
+	return 0;
+}
+
+static inline size_t zstd_decompress_stream(struct zstd_data *data __maybe_unused, void *src __maybe_unused,
+					    size_t src_size __maybe_unused, void *dst __maybe_unused,
+					    size_t dst_size __maybe_unused)
+{
+	return 0;
+}
+#endif
+
+#endif /* PERF_COMPRESS_H */