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, 67 insertions, 0 deletions

diff --git a/fs/xfs/scrub/bitmap.h b/fs/xfs/scrub/bitmap.h
new file mode 100644
index 000000000..710c1ac5e
--- /dev/null
+++ b/fs/xfs/scrub/bitmap.h
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2018-2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_BITMAP_H__
+#define __XFS_SCRUB_BITMAP_H__
+
+/* u64 bitmap */
+
+struct xbitmap64 {
+	struct rb_root_cached	xb_root;
+};
+
+void xbitmap64_init(struct xbitmap64 *bitmap);
+void xbitmap64_destroy(struct xbitmap64 *bitmap);
+
+int xbitmap64_clear(struct xbitmap64 *bitmap, uint64_t start, uint64_t len);
+int xbitmap64_set(struct xbitmap64 *bitmap, uint64_t start, uint64_t len);
+int xbitmap64_disunion(struct xbitmap64 *bitmap, struct xbitmap64 *sub);
+uint64_t xbitmap64_hweight(struct xbitmap64 *bitmap);
+
+/*
+ * Return codes for the bitmap iterator functions are 0 to continue iterating,
+ * and non-zero to stop iterating.  Any non-zero value will be passed up to the
+ * iteration caller.  The special value -ECANCELED can be used to stop
+ * iteration, because neither bitmap iterator ever generates that error code on
+ * its own.  Callers must not modify the bitmap while walking it.
+ */
+typedef int (*xbitmap64_walk_fn)(uint64_t start, uint64_t len, void *priv);
+int xbitmap64_walk(struct xbitmap64 *bitmap, xbitmap64_walk_fn fn,
+		void *priv);
+
+bool xbitmap64_empty(struct xbitmap64 *bitmap);
+bool xbitmap64_test(struct xbitmap64 *bitmap, uint64_t start, uint64_t *len);
+
+/* u32 bitmap */
+
+struct xbitmap32 {
+	struct rb_root_cached	xb_root;
+};
+
+void xbitmap32_init(struct xbitmap32 *bitmap);
+void xbitmap32_destroy(struct xbitmap32 *bitmap);
+
+int xbitmap32_clear(struct xbitmap32 *bitmap, uint32_t start, uint32_t len);
+int xbitmap32_set(struct xbitmap32 *bitmap, uint32_t start, uint32_t len);
+int xbitmap32_disunion(struct xbitmap32 *bitmap, struct xbitmap32 *sub);
+uint32_t xbitmap32_hweight(struct xbitmap32 *bitmap);
+
+/*
+ * Return codes for the bitmap iterator functions are 0 to continue iterating,
+ * and non-zero to stop iterating.  Any non-zero value will be passed up to the
+ * iteration caller.  The special value -ECANCELED can be used to stop
+ * iteration, because neither bitmap iterator ever generates that error code on
+ * its own.  Callers must not modify the bitmap while walking it.
+ */
+typedef int (*xbitmap32_walk_fn)(uint32_t start, uint32_t len, void *priv);
+int xbitmap32_walk(struct xbitmap32 *bitmap, xbitmap32_walk_fn fn,
+		void *priv);
+
+bool xbitmap32_empty(struct xbitmap32 *bitmap);
+bool xbitmap32_test(struct xbitmap32 *bitmap, uint32_t start, uint32_t *len);
+
+uint32_t xbitmap32_count_set_regions(struct xbitmap32 *bitmap);
+
+#endif	/* __XFS_SCRUB_BITMAP_H__ */