linux-kernel - [PATCH 1/2] hfs: fix potential refcnt problem of nls module

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Date:   Tue, 17 Apr 2018 15:05:32 +0800
From:   Chengguang Xu <cgxu519@....com>
To:     linux-fsdevel@...r.kernel.org
Cc:     dhowells@...hat.com, kstewart@...uxfoundation.org,
        gregkh@...uxfoundation.org, tglx@...utronix.de,
        pombredanne@...b.com, linux-kernel@...r.kernel.org,
        Chengguang Xu <cgxu519@....com>
Subject: [PATCH 1/2] hfs: fix potential refcnt problem of nls module

When specifying iocharset/codepage multiple times in a mount,
current option parsing will cause inaccurate refcount of nls
module. Hence, call unload_nls for previous one in this case.

Signed-off-by: Chengguang Xu <cgxu519@....com>
---
 fs/hfs/super.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/hfs/super.c b/fs/hfs/super.c
index 1738767..6a5f6fd 100644
--- a/fs/hfs/super.c
+++ b/fs/hfs/super.c
@@ -329,8 +329,10 @@ static int parse_options(char *options, struct hfs_sb_info *hsb)
 				return 0;
 			}
 			p = match_strdup(&args[0]);
-			if (p)
+			if (p) {
+				unload_nls(hsb->nls_disk);
 				hsb->nls_disk = load_nls(p);
+			}
 			if (!hsb->nls_disk) {
 				pr_err("unable to load codepage \"%s\"\n", p);
 				kfree(p);
@@ -344,8 +346,10 @@ static int parse_options(char *options, struct hfs_sb_info *hsb)
 				return 0;
 			}
 			p = match_strdup(&args[0]);
-			if (p)
+			if (p) {
+				unload_nls(hsb->nls_io);
 				hsb->nls_io = load_nls(p);
+			}
 			if (!hsb->nls_io) {
 				pr_err("unable to load iocharset \"%s\"\n", p);
 				kfree(p);
-- 
1.8.3.1