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, 43 insertions, 0 deletions

diff --git a/fs/jffs2/acl.h b/fs/jffs2/acl.h
new file mode 100644
index 000000000..e976b8cb8
--- /dev/null
+++ b/fs/jffs2/acl.h
@@ -0,0 +1,43 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2006  NEC Corporation
+ *
+ * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+struct jffs2_acl_entry {
+	jint16_t	e_tag;
+	jint16_t	e_perm;
+	jint32_t	e_id;
+};
+
+struct jffs2_acl_entry_short {
+	jint16_t	e_tag;
+	jint16_t	e_perm;
+};
+
+struct jffs2_acl_header {
+	jint32_t	a_version;
+	struct jffs2_acl_entry	a_entries[];
+};
+
+#ifdef CONFIG_JFFS2_FS_POSIX_ACL
+
+struct posix_acl *jffs2_get_acl(struct inode *inode, int type, bool rcu);
+int jffs2_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+		  struct posix_acl *acl, int type);
+extern int jffs2_init_acl_pre(struct inode *, struct inode *, umode_t *);
+extern int jffs2_init_acl_post(struct inode *);
+
+#else
+
+#define jffs2_get_acl				(NULL)
+#define jffs2_set_acl				(NULL)
+#define jffs2_init_acl_pre(dir_i,inode,mode)	(0)
+#define jffs2_init_acl_post(inode)		(0)
+
+#endif	/* CONFIG_JFFS2_FS_POSIX_ACL */