2 files changed, 20 insertions, 1 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2fbdff6be25c..e14512678c9b 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -1020,6 +1020,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
                 ino = parent_sd->s_ino;
                 if (filldir(dirent, ".", 1, filp->f_pos, ino, DT_DIR) == 0)
                         filp->f_pos++;
+                else
+                        return 0;
         }
         if (filp->f_pos == 1) {
                 if (parent_sd->s_parent)
@@ -1028,6 +1030,8 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
                         ino = parent_sd->s_ino;
                 if (filldir(dirent, "..", 2, filp->f_pos, ino, DT_DIR) == 0)
                         filp->f_pos++;
+                else
+                        return 0;
         }
         mutex_lock(&sysfs_mutex);
         for (pos = sysfs_dir_pos(ns, parent_sd, filp->f_pos, pos);
@@ -1058,10 +1062,21 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
         return 0;
 }
 
+static loff_t sysfs_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+        struct inode *inode = file_inode(file);
+        loff_t ret;
+
+        mutex_lock(&inode->i_mutex);
+        ret = generic_file_llseek(file, offset, whence);
+        mutex_unlock(&inode->i_mutex);
+
+        return ret;
+}
 
 const struct file_operations sysfs_dir_operations = {
         .read           = generic_read_dir,
         .readdir        = sysfs_readdir,
         .release        = sysfs_dir_release,
-        .llseek         = generic_file_llseek,
+        .llseek         = sysfs_dir_llseek,
 };
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 8d924b5ec733..afd83273e6ce 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <linux/user_namespace.h>
 
 #include "sysfs.h"
 
@@ -111,6 +112,9 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
         struct super_block *sb;
         int error;
 
+        if (!(flags & MS_KERNMOUNT) && !current_user_ns()->may_mount_sysfs)
+                return ERR_PTR(-EPERM);
+
         info = kzalloc(sizeof(*info), GFP_KERNEL);
         if (!info)
                 return ERR_PTR(-ENOMEM);