linux-kernel - [PATCH v4 2/5] fs: Check if utf8 encoding is loaded before calling utf8

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Date:   Thu, 25 Mar 2021 05:38:08 +0530
From:   Shreeya Patel <shreeya.patel@...labora.com>
To:     tytso@....edu, adilger.kernel@...ger.ca, jaegeuk@...nel.org,
        chao@...nel.org, krisman@...labora.com, ebiggers@...gle.com,
        drosen@...gle.com, ebiggers@...nel.org, yuchao0@...wei.com
Cc:     linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, kernel@...labora.com,
        andre.almeida@...labora.com
Subject: [PATCH v4 2/5] fs: Check if utf8 encoding is loaded before calling utf8_unload()

utf8_unload is being called if CONFIG_UNICODE is enabled.
The ifdef block doesn't check if utf8 encoding has been loaded
or not before calling the utf8_unload() function.
This is not the expected behavior since it would sometimes lead
to unloading utf8 even before loading it.
Hence, add a condition which will check if sb->encoding is NOT NULL
before calling the utf8_unload().

Reviewed-by: Gabriel Krisman Bertazi <krisman@...labora.com>
Signed-off-by: Shreeya Patel <shreeya.patel@...labora.com>
---
 fs/ext4/super.c | 6 ++++--
 fs/f2fs/super.c | 9 ++++++---
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ad34a37278cd..e438d14f9a87 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1259,7 +1259,8 @@ static void ext4_put_super(struct super_block *sb)
 	fs_put_dax(sbi->s_daxdev);
 	fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy);
 #ifdef CONFIG_UNICODE
-	utf8_unload(sb->s_encoding);
+	if (sb->s_encoding)
+		utf8_unload(sb->s_encoding);
 #endif
 	kfree(sbi);
 }
@@ -5165,7 +5166,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		crypto_free_shash(sbi->s_chksum_driver);
 
 #ifdef CONFIG_UNICODE
-	utf8_unload(sb->s_encoding);
+	if (sb->s_encoding)
+		utf8_unload(sb->s_encoding);
 #endif
 
 #ifdef CONFIG_QUOTA
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 7069793752f1..0a04983c294e 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1430,7 +1430,8 @@ static void f2fs_put_super(struct super_block *sb)
 	for (i = 0; i < NR_PAGE_TYPE; i++)
 		kvfree(sbi->write_io[i]);
 #ifdef CONFIG_UNICODE
-	utf8_unload(sb->s_encoding);
+	if (sb->s_encoding)
+		utf8_unload(sb->s_encoding);
 #endif
 	kfree(sbi);
 }
@@ -4073,8 +4074,10 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 		kvfree(sbi->write_io[i]);
 
 #ifdef CONFIG_UNICODE
-	utf8_unload(sb->s_encoding);
-	sb->s_encoding = NULL;
+	if (sb->s_encoding) {
+		utf8_unload(sb->s_encoding);
+		sb->s_encoding = NULL;
+	}
 #endif
 free_options:
 #ifdef CONFIG_QUOTA
-- 
2.30.1