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, 29 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
new file mode 100644
index 000000000..ccf6bed9c
--- /dev/null
+++ b/fs/btrfs/ioctl.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_IOCTL_H
+#define BTRFS_IOCTL_H
+
+#include <linux/types.h>
+
+struct file;
+struct dentry;
+struct mnt_idmap;
+struct file_kattr;
+struct io_uring_cmd;
+struct btrfs_inode;
+struct btrfs_fs_info;
+struct btrfs_ioctl_balance_args;
+
+long btrfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+long btrfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+int btrfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
+int btrfs_fileattr_set(struct mnt_idmap *idmap,
+		       struct dentry *dentry, struct file_kattr *fa);
+int btrfs_ioctl_get_supported_features(void __user *arg);
+void btrfs_sync_inode_flags_to_i_flags(struct btrfs_inode *inode);
+void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
+				     struct btrfs_ioctl_balance_args *bargs);
+int btrfs_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags);
+void btrfs_uring_read_extent_endio(void *ctx, int err);
+
+#endif