linux-ext4 - [PATCH v3 1/5] fs: unicode: Use strscpy() instead of strncpy()

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Date:   Wed, 24 Mar 2021 00:01:57 +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, kernel test robot <lkp@...el.com>
Subject: [PATCH v3 1/5] fs: unicode: Use strscpy() instead of strncpy()

Following warning was reported by Kernel Test Robot.

In function 'utf8_parse_version',
inlined from 'utf8_load' at fs/unicode/utf8mod.c:195:7:
>> fs/unicode/utf8mod.c:175:2: warning: 'strncpy' specified bound 12 equals
destination size [-Wstringop-truncation]
175 |  strncpy(version_string, version, sizeof(version_string));
    |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The -Wstringop-truncation warning highlights the unintended
uses of the strncpy function that truncate the terminating NULL
character from the source string.
Unlike strncpy(), strscpy() always null-terminates the destination string,
hence use strscpy() instead of strncpy().

Fixes: 9d53690f0d4e5 (unicode: implement higher level API for string handling)
Signed-off-by: Shreeya Patel <shreeya.patel@...labora.com>
Reported-by: kernel test robot <lkp@...el.com>
---

Changes in v3
  - Return error if strscpy() returns value < 0

Changes in v2
  - Resolve warning of -Wstringop-truncation reported by
    kernel test robot.

 fs/unicode/utf8-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
index dc25823bf..706f086bb 100644
--- a/fs/unicode/utf8-core.c
+++ b/fs/unicode/utf8-core.c
@@ -180,7 +180,10 @@ static int utf8_parse_version(const char *version, unsigned int *maj,
 		{0, NULL}
 	};
 
-	strncpy(version_string, version, sizeof(version_string));
+	int ret = strscpy(version_string, version, sizeof(version_string));
+
+	if (ret < 0)
+		return ret;
 
 	if (match_token(version_string, token, args) != 1)
 		return -EINVAL;
-- 
2.24.3 (Apple Git-128)