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, 32 insertions, 0 deletions

diff --git a/fs/ntfs3/lib/lib.h b/fs/ntfs3/lib/lib.h
new file mode 100644
index 000000000..90309a5ae
--- /dev/null
+++ b/fs/ntfs3/lib/lib.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Adapted for linux kernel by Alexander Mamaev:
+ * - remove implementations of get_unaligned_
+ * - assume GCC is always defined
+ * - ISO C90
+ * - linux kernel code style
+ */
+
+#ifndef _LINUX_NTFS3_LIB_LIB_H
+#define _LINUX_NTFS3_LIB_LIB_H
+
+#include <linux/types.h>
+
+/* globals from xpress_decompress.c */
+struct xpress_decompressor *xpress_allocate_decompressor(void);
+void xpress_free_decompressor(struct xpress_decompressor *d);
+int xpress_decompress(struct xpress_decompressor *__restrict d,
+		      const void *__restrict compressed_data,
+		      size_t compressed_size,
+		      void *__restrict uncompressed_data,
+		      size_t uncompressed_size);
+
+/* globals from lzx_decompress.c */
+struct lzx_decompressor *lzx_allocate_decompressor(void);
+void lzx_free_decompressor(struct lzx_decompressor *d);
+int lzx_decompress(struct lzx_decompressor *__restrict d,
+		   const void *__restrict compressed_data,
+		   size_t compressed_size, void *__restrict uncompressed_data,
+		   size_t uncompressed_size);
+
+#endif /* _LINUX_NTFS3_LIB_LIB_H */