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, 51 insertions, 0 deletions

diff --git a/fs/btrfs/file.h b/fs/btrfs/file.h
new file mode 100644
index 000000000..d7df81388
--- /dev/null
+++ b/fs/btrfs/file.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_FILE_H
+#define BTRFS_FILE_H
+
+#include <linux/types.h>
+
+struct file;
+struct extent_state;
+struct kiocb;
+struct iov_iter;
+struct inode;
+struct folio;
+struct page;
+struct btrfs_ioctl_encoded_io_args;
+struct btrfs_drop_extents_args;
+struct btrfs_inode;
+struct btrfs_root;
+struct btrfs_path;
+struct btrfs_replace_extent_info;
+struct btrfs_trans_handle;
+
+extern const struct file_operations btrfs_file_operations;
+
+int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync);
+int btrfs_drop_extents(struct btrfs_trans_handle *trans,
+		       struct btrfs_root *root, struct btrfs_inode *inode,
+		       struct btrfs_drop_extents_args *args);
+int btrfs_replace_file_extents(struct btrfs_inode *inode,
+			   struct btrfs_path *path, const u64 start,
+			   const u64 end,
+			   struct btrfs_replace_extent_info *extent_info,
+			   struct btrfs_trans_handle **trans_out);
+int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
+			      struct btrfs_inode *inode, u64 start, u64 end);
+ssize_t btrfs_do_write_iter(struct kiocb *iocb, struct iov_iter *from,
+			    const struct btrfs_ioctl_encoded_io_args *encoded);
+int btrfs_release_file(struct inode *inode, struct file *file);
+int btrfs_dirty_folio(struct btrfs_inode *inode, struct folio *folio, loff_t pos,
+		      size_t write_bytes, struct extent_state **cached, bool noreserve);
+int btrfs_fdatawrite_range(struct btrfs_inode *inode, loff_t start, loff_t end);
+int btrfs_check_nocow_lock(struct btrfs_inode *inode, loff_t pos,
+			   size_t *write_bytes, bool nowait);
+void btrfs_check_nocow_unlock(struct btrfs_inode *inode);
+bool btrfs_find_delalloc_in_range(struct btrfs_inode *inode, u64 start, u64 end,
+				  struct extent_state **cached_state,
+				  u64 *delalloc_start_ret, u64 *delalloc_end_ret);
+int btrfs_write_check(struct kiocb *iocb, size_t count);
+ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i);
+
+#endif