udf: fix potential refcnt problem of nls module

When specifiying iocharset multiple times in a mount or once/multiple in
a remount, current option parsing may cause inaccurate refcount of nls
module.  Also, in the failure cleanup of option parsing, the condition
of calling unload_nls is not sufficient.

Signed-off-by: Chengguang Xu <cgxu519@icloud.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/udf/super.c b/fs/udf/super.c
index bf5f6084dcb2047d070cf72e09a4b98060abfa5c..7949c338efa5491d9d8b4a0fbe69233c07b75ce3 100644 (file)
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -477,7 +477,6 @@ static int udf_parse_options(char *options, struct udf_options *uopt,
        uopt->session = 0xFFFFFFFF;
        uopt->lastblock = 0;
        uopt->anchor = 0;
-       uopt->nls_map = NULL;
 
        if (!options)
                return 1;
@@ -575,8 +574,12 @@ static int udf_parse_options(char *options, struct udf_options *uopt,
                        break;
 #ifdef CONFIG_UDF_NLS
                case Opt_iocharset:
-                       uopt->nls_map = load_nls(args[0].from);
-                       uopt->flags |= (1 << UDF_FLAG_NLS_MAP);
+                       if (!remount) {
+                               if (uopt->nls_map)
+                                       unload_nls(uopt->nls_map);
+                               uopt->nls_map = load_nls(args[0].from);
+                               uopt->flags |= (1 << UDF_FLAG_NLS_MAP);
+                       }
                        break;
 #endif
                case Opt_uforget:
@@ -627,6 +630,7 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
        uopt.umask = sbi->s_umask;
        uopt.fmode = sbi->s_fmode;
        uopt.dmode = sbi->s_dmode;
+       uopt.nls_map = NULL;
 
        if (!udf_parse_options(options, &uopt, true))
                return -EINVAL;
@@ -2095,6 +2099,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
        uopt.umask = 0;
        uopt.fmode = UDF_INVALID_MODE;
        uopt.dmode = UDF_INVALID_MODE;
+       uopt.nls_map = NULL;
 
        sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
        if (!sbi)
@@ -2275,8 +2280,8 @@ error_out:
        iput(sbi->s_vat_inode);
 parse_options_failure:
 #ifdef CONFIG_UDF_NLS
-       if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP))
-               unload_nls(sbi->s_nls_map);
+       if (uopt.nls_map)
+               unload_nls(uopt.nls_map);
 #endif
        if (lvid_open)
                udf_close_lvid(sb);