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, 71 insertions, 0 deletions

diff --git a/fs/gfs2/bmap.h b/fs/gfs2/bmap.h
new file mode 100644
index 000000000..e3d6efdfd
--- /dev/null
+++ b/fs/gfs2/bmap.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ */
+
+#ifndef __BMAP_DOT_H__
+#define __BMAP_DOT_H__
+
+#include <linux/iomap.h>
+
+#include "inode.h"
+
+struct inode;
+struct gfs2_inode;
+struct page;
+
+
+/**
+ * gfs2_write_calc_reserv - calculate number of blocks needed to write to a file
+ * @ip: the file
+ * @len: the number of bytes to be written to the file
+ * @data_blocks: returns the number of data blocks required
+ * @ind_blocks: returns the number of indirect blocks required
+ *
+ */
+
+static inline void gfs2_write_calc_reserv(const struct gfs2_inode *ip,
+					  unsigned int len,
+					  unsigned int *data_blocks,
+					  unsigned int *ind_blocks)
+{
+	const struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
+	unsigned int tmp;
+
+	BUG_ON(gfs2_is_dir(ip));
+	*data_blocks = (len >> sdp->sd_sb.sb_bsize_shift) + 3;
+	*ind_blocks = 3 * (sdp->sd_max_height - 1);
+
+	for (tmp = *data_blocks; tmp > sdp->sd_diptrs;) {
+		tmp = DIV_ROUND_UP(tmp, sdp->sd_inptrs);
+		*ind_blocks += tmp;
+	}
+}
+
+extern const struct iomap_ops gfs2_iomap_ops;
+extern const struct iomap_write_ops gfs2_iomap_write_ops;
+extern const struct iomap_writeback_ops gfs2_writeback_ops;
+
+int gfs2_unstuff_dinode(struct gfs2_inode *ip);
+int gfs2_block_map(struct inode *inode, sector_t lblock,
+		   struct buffer_head *bh, int create);
+int gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length,
+		   struct iomap *iomap);
+int gfs2_iomap_alloc(struct inode *inode, loff_t pos, loff_t length,
+		     struct iomap *iomap);
+int gfs2_get_extent(struct inode *inode, u64 lblock, u64 *dblock,
+		    unsigned int *extlen);
+int gfs2_alloc_extent(struct inode *inode, u64 lblock, u64 *dblock,
+		      unsigned *extlen, bool *new);
+int gfs2_clear_beyond_eof(struct inode *inode, loff_t end);
+int gfs2_setattr_size(struct inode *inode, u64 size);
+int gfs2_truncatei_resume(struct gfs2_inode *ip);
+int gfs2_file_dealloc(struct gfs2_inode *ip);
+int gfs2_write_alloc_required(struct gfs2_inode *ip, u64 offset,
+			      unsigned int len);
+int gfs2_map_journal_extents(struct gfs2_sbd *sdp, struct gfs2_jdesc *jd);
+void gfs2_free_journal_extents(struct gfs2_jdesc *jd);
+int __gfs2_punch_hole(struct file *file, loff_t offset, loff_t length);
+
+#endif /* __BMAP_DOT_H__ */