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, 57 insertions, 0 deletions

diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
new file mode 100644
index 000000000..05498e534
--- /dev/null
+++ b/fs/btrfs/sysfs.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_SYSFS_H
+#define BTRFS_SYSFS_H
+
+#include <linux/types.h>
+#include <linux/compiler_types.h>
+#include <linux/kobject.h>
+
+struct block_device;
+struct btrfs_fs_info;
+struct btrfs_device;
+struct btrfs_fs_devices;
+struct btrfs_block_group;
+struct btrfs_space_info;
+struct btrfs_qgroup;
+
+enum btrfs_feature_set {
+	FEAT_COMPAT,
+	FEAT_COMPAT_RO,
+	FEAT_INCOMPAT,
+	FEAT_MAX
+};
+
+char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags);
+const char *btrfs_feature_set_name(enum btrfs_feature_set set);
+int btrfs_sysfs_add_device(struct btrfs_device *device);
+void btrfs_sysfs_remove_device(struct btrfs_device *device);
+int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs);
+void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs);
+void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices);
+void btrfs_sysfs_feature_update(struct btrfs_fs_info *fs_info);
+void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action);
+
+int __init btrfs_init_sysfs(void);
+void __cold btrfs_exit_sysfs(void);
+int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info);
+void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info);
+void btrfs_sysfs_add_block_group_type(struct btrfs_block_group *cache);
+int btrfs_sysfs_add_space_info_type(struct btrfs_space_info *space_info);
+void btrfs_sysfs_remove_space_info(struct btrfs_space_info *space_info);
+void btrfs_sysfs_update_devid(struct btrfs_device *device);
+
+int btrfs_sysfs_add_one_qgroup(struct btrfs_fs_info *fs_info,
+				struct btrfs_qgroup *qgroup);
+void btrfs_sysfs_del_qgroups(struct btrfs_fs_info *fs_info);
+int btrfs_sysfs_add_qgroups(struct btrfs_fs_info *fs_info);
+void btrfs_sysfs_del_one_qgroup(struct btrfs_fs_info *fs_info,
+				struct btrfs_qgroup *qgroup);
+int btrfs_read_policy_to_enum(const char *str, s64 *value);
+
+#ifdef CONFIG_BTRFS_EXPERIMENTAL
+int __init btrfs_read_policy_init(void);
+char *btrfs_get_mod_read_policy(void);
+#endif
+
+#endif