[PATCH] fscrypto: fix to null-terminate encrypted filename in fname_encrypt

[Chao Yu]

From: Chao Yu <yuch...@huawei.com>

This patch fixes to add null character at the end of encrypted filename
in fname_encrypt, in order to avoid incorrectly traversing random data
located after target filename. The call stack is as below:

- f2fs_add_link
 - __f2fs_add_link
  - fscrypt_setup_filename
   - fscrypt_fname_alloc_buffer         allocate buffer for @fname
   - fname_encrypt                      didn't set null character for @fname
  - f2fs_add_regular_entry              init qstr with @fname
   - init_inode_metadata
    - f2fs_init_security
     - security_inode_init_security
      - selinux_inode_init_security
       - selinux_determine_inode_label
        - security_transition_sid
         - security_compute_sid
          - filename_compute_type
           - hashtab_search
            - filenametr_hash           traverse @fname as one which has null 
character

Signed-off-by: Chao Yu <yuch...@huawei.com>
---
 fs/crypto/fname.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c
index 5d6d491..5c356c0 100644
--- a/fs/crypto/fname.c
+++ b/fs/crypto/fname.c
@@ -110,6 +110,7 @@ static int fname_encrypt(struct inode *inode,
                                "%s: Error (error code %d)\n", __func__, res);
 
        oname->len = ciphertext_len;
+       oname->name[oname->len] = 0;
        return res;
 }
 
-- 
2.7.2