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, 106 insertions, 0 deletions

diff --git a/fs/zonefs/trace.h b/fs/zonefs/trace.h
new file mode 100644
index 000000000..7315a72ca
--- /dev/null
+++ b/fs/zonefs/trace.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * zonefs filesystem driver tracepoints.
+ *
+ * Copyright (C) 2021 Western Digital Corporation or its affiliates.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM zonefs
+
+#if !defined(_TRACE_ZONEFS_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ZONEFS_H
+
+#include <linux/tracepoint.h>
+#include <linux/trace_seq.h>
+#include <linux/blkdev.h>
+
+#include "zonefs.h"
+
+#define show_dev(dev) MAJOR(dev), MINOR(dev)
+
+TRACE_EVENT(zonefs_zone_mgmt,
+	    TP_PROTO(struct super_block *sb, struct zonefs_zone *z,
+		     enum req_op op),
+	    TP_ARGS(sb, z, op),
+	    TP_STRUCT__entry(
+			     __field(dev_t, dev)
+			     __field(u64, ino)
+			     __field(enum req_op, op)
+			     __field(sector_t, sector)
+			     __field(sector_t, nr_sectors)
+	    ),
+	    TP_fast_assign(
+			   __entry->dev = sb->s_dev;
+			   __entry->ino =
+				z->z_sector >> ZONEFS_SB(sb)->s_zone_sectors_shift;
+			   __entry->op = op;
+			   __entry->sector = z->z_sector;
+			   __entry->nr_sectors = z->z_size >> SECTOR_SHIFT;
+	    ),
+	    TP_printk("bdev=(%d,%d), ino=%llu op=%s, sector=%llu, nr_sectors=%llu",
+		      show_dev(__entry->dev), __entry->ino,
+		      blk_op_str(__entry->op), __entry->sector,
+		      __entry->nr_sectors
+	    )
+);
+
+TRACE_EVENT(zonefs_file_dio_append,
+	    TP_PROTO(struct inode *inode, ssize_t size, ssize_t ret),
+	    TP_ARGS(inode, size, ret),
+	    TP_STRUCT__entry(
+			     __field(dev_t, dev)
+			     __field(u64, ino)
+			     __field(sector_t, sector)
+			     __field(ssize_t, size)
+			     __field(loff_t, wpoffset)
+			     __field(ssize_t, ret)
+	    ),
+	    TP_fast_assign(
+			   __entry->dev = inode->i_sb->s_dev;
+			   __entry->ino = inode->i_ino;
+			   __entry->sector = zonefs_inode_zone(inode)->z_sector;
+			   __entry->size = size;
+			   __entry->wpoffset =
+				zonefs_inode_zone(inode)->z_wpoffset;
+			   __entry->ret = ret;
+	    ),
+	    TP_printk("bdev=(%d, %d), ino=%llu, sector=%llu, size=%zu, wpoffset=%llu, ret=%zu",
+		      show_dev(__entry->dev), __entry->ino,
+		      __entry->sector, __entry->size, __entry->wpoffset,
+		      __entry->ret
+	    )
+);
+
+TRACE_EVENT(zonefs_iomap_begin,
+	    TP_PROTO(struct inode *inode, struct iomap *iomap),
+	    TP_ARGS(inode, iomap),
+	    TP_STRUCT__entry(
+			     __field(dev_t, dev)
+			     __field(u64, ino)
+			     __field(u64, addr)
+			     __field(loff_t, offset)
+			     __field(u64, length)
+	    ),
+	    TP_fast_assign(
+			   __entry->dev = inode->i_sb->s_dev;
+			   __entry->ino = inode->i_ino;
+			   __entry->addr = iomap->addr;
+			   __entry->offset = iomap->offset;
+			   __entry->length = iomap->length;
+	    ),
+	    TP_printk("bdev=(%d,%d), ino=%llu, addr=%llu, offset=%llu, length=%llu",
+		      show_dev(__entry->dev), __entry->ino,
+		      __entry->addr, __entry->offset, __entry->length
+	    )
+);
+
+#endif /* _TRACE_ZONEFS_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>