1 files changed, 18 insertions, 6 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index d8325263ba6e..93bc0f8174a7 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -640,8 +640,9 @@ static int
 ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
 {
         char *lower_buf;
+        size_t lower_bufsiz;
         struct dentry *lower_dentry;
-        struct ecryptfs_crypt_stat *crypt_stat;
+        struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
         char *plaintext_name;
         size_t plaintext_name_size;
         mm_segment_t old_fs;
@@ -652,12 +653,21 @@ ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
                 rc = -EINVAL;
                 goto out;
         }
-        crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
+        mount_crypt_stat = &ecryptfs_superblock_to_private(
+                                                dentry->d_sb)->mount_crypt_stat;
+        /*
+         * If the lower filename is encrypted, it will result in a significantly
+         * longer name.  If needed, truncate the name after decode and decrypt.
+         */
+        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
+                lower_bufsiz = PATH_MAX;
+        else
+                lower_bufsiz = bufsiz;
         /* Released in this function */
-        lower_buf = kmalloc(bufsiz, GFP_KERNEL);
+        lower_buf = kmalloc(lower_bufsiz, GFP_KERNEL);
         if (lower_buf == NULL) {
                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
-                       "kmalloc [%d] bytes\n", __func__, bufsiz);
+                       "kmalloc [%d] bytes\n", __func__, lower_bufsiz);
                 rc = -ENOMEM;
                 goto out;
         }
@@ -665,7 +675,7 @@ ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
         set_fs(get_ds());
         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
                                                    (char __user *)lower_buf,
-                                                   bufsiz);
+                                                   lower_bufsiz);
         set_fs(old_fs);
         if (rc >= 0) {
                 rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
@@ -678,7 +688,9 @@ ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
                                 rc);
                         goto out_free_lower_buf;
                 }
-                rc = copy_to_user(buf, plaintext_name, plaintext_name_size);
+                /* Check for bufsiz <= 0 done in sys_readlinkat() */
+                rc = copy_to_user(buf, plaintext_name,
+                                  min((unsigned) bufsiz, plaintext_name_size));
                 if (rc)
                         rc = -EFAULT;
                 else