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, 66 insertions, 0 deletions

diff --git a/fs/smb/server/misc.h b/fs/smb/server/misc.h
new file mode 100644
index 000000000..3909104e1
--- /dev/null
+++ b/fs/smb/server/misc.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __KSMBD_MISC_H__
+#define __KSMBD_MISC_H__
+
+#ifdef CONFIG_PROC_FS
+#include <linux/proc_fs.h>
+#endif
+struct ksmbd_share_config;
+struct nls_table;
+struct kstat;
+struct ksmbd_file;
+
+int match_pattern(const char *str, size_t len, const char *pattern);
+int ksmbd_validate_filename(char *filename);
+int parse_stream_name(char *filename, char **stream_name, int *s_type);
+char *convert_to_nt_pathname(struct ksmbd_share_config *share,
+			     const struct path *path);
+int get_nlink(struct kstat *st);
+void ksmbd_conv_path_to_unix(char *path);
+void ksmbd_strip_last_slash(char *path);
+void ksmbd_conv_path_to_windows(char *path);
+char *ksmbd_casefold_sharename(struct unicode_map *um, const char *name);
+char *ksmbd_extract_sharename(struct unicode_map *um, const char *treename);
+
+#define KSMBD_DIR_INFO_ALIGNMENT	8
+struct ksmbd_dir_info;
+char *ksmbd_convert_dir_info_name(struct ksmbd_dir_info *d_info,
+				  const struct nls_table *local_nls,
+				  int *conv_len);
+
+#define NTFS_TIME_OFFSET	((u64)(369 * 365 + 89) * 24 * 3600 * 10000000)
+struct timespec64 ksmbd_NTtimeToUnix(__le64 ntutc);
+u64 ksmbd_UnixTimeToNT(struct timespec64 t);
+long long ksmbd_systime(void);
+
+#ifdef CONFIG_PROC_FS
+struct ksmbd_const_name {
+	unsigned int const_value;
+	const char *name;
+};
+
+void ksmbd_proc_init(void);
+void ksmbd_proc_cleanup(void);
+void ksmbd_proc_reset(void);
+struct proc_dir_entry *ksmbd_proc_create(const char *name,
+					 int (*show)(struct seq_file *m, void *v),
+			     void *v);
+void ksmbd_proc_show_flag_names(struct seq_file *m,
+				const struct ksmbd_const_name *table,
+				int count,
+				unsigned int flags);
+void ksmbd_proc_show_const_name(struct seq_file *m,
+				const char *format,
+				const struct ksmbd_const_name *table,
+				int count,
+				unsigned int const_value);
+#else
+static inline void ksmbd_proc_init(void) {}
+static inline void ksmbd_proc_cleanup(void) {}
+static inline void ksmbd_proc_reset(void) {}
+#endif
+#endif /* __KSMBD_MISC_H__ */