1 files changed, 24 insertions, 7 deletions

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index add566303c68..c35ffdc12bba 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -142,6 +142,8 @@ static inline struct super_block *pts_sb_from_inode(struct inode *inode)
         if (inode->i_sb->s_magic == DEVPTS_SUPER_MAGIC)
                 return inode->i_sb;
 #endif
+        if (!devpts_mnt)
+                return NULL;
         return devpts_mnt->mnt_sb;
 }
 
@@ -525,10 +527,14 @@ static struct file_system_type devpts_fs_type = {
 int devpts_new_index(struct inode *ptmx_inode)
 {
         struct super_block *sb = pts_sb_from_inode(ptmx_inode);
-        struct pts_fs_info *fsi = DEVPTS_SB(sb);
+        struct pts_fs_info *fsi;
         int index;
         int ida_ret;
 
+        if (!sb)
+                return -ENODEV;
+
+        fsi = DEVPTS_SB(sb);
 retry:
         if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
                 return -ENOMEM;
@@ -584,11 +590,18 @@ struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int index,
         struct dentry *dentry;
         struct super_block *sb = pts_sb_from_inode(ptmx_inode);
         struct inode *inode;
-        struct dentry *root = sb->s_root;
-        struct pts_fs_info *fsi = DEVPTS_SB(sb);
-        struct pts_mount_opts *opts = &fsi->mount_opts;
+        struct dentry *root;
+        struct pts_fs_info *fsi;
+        struct pts_mount_opts *opts;
         char s[12];
 
+        if (!sb)
+                return ERR_PTR(-ENODEV);
+
+        root = sb->s_root;
+        fsi = DEVPTS_SB(sb);
+        opts = &fsi->mount_opts;
+
         inode = new_inode(sb);
         if (!inode)
                 return ERR_PTR(-ENOMEM);
@@ -676,12 +689,16 @@ static int __init init_devpts_fs(void)
         struct ctl_table_header *table;
 
         if (!err) {
+                struct vfsmount *mnt;
+
                 table = register_sysctl_table(pty_root_table);
-                devpts_mnt = kern_mount(&devpts_fs_type);
-                if (IS_ERR(devpts_mnt)) {
-                        err = PTR_ERR(devpts_mnt);
+                mnt = kern_mount(&devpts_fs_type);
+                if (IS_ERR(mnt)) {
+                        err = PTR_ERR(mnt);
                         unregister_filesystem(&devpts_fs_type);
                         unregister_sysctl_table(table);
+                } else {
+                        devpts_mnt = mnt;
                 }
         }
         return err;