[PATCH v8 1/4] fs: unicode: Use strscpy() instead of strncpy()

[Shreeya Patel]

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 if source string is longer than the destination size.

strscpy() returns -E2BIG error code in case the source string doesn't
fit into the destination. Hence, use strscpy() and return an error for
overly-long strings instead of creating a non-null-terminated string
with strncpy().

Fixes: 9d53690f0d4e5 (unicode: implement higher level API for string handling)
Acked-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxx>
Signed-off-by: Shreeya Patel <shreeya.patel@xxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
---
Changes in v8
  - Improve the commit message to decribe about how overly-long strings
    are handled.

 fs/unicode/utf8-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
index dc25823bfed9..f9e6a2718aba 100644
--- a/fs/unicode/utf8-core.c
+++ b/fs/unicode/utf8-core.c
@@ -179,8 +179,10 @@ static int utf8_parse_version(const char *version, unsigned int *maj,
 		{1, "%d.%d.%d"},
 		{0, NULL}
 	};
+	int ret = strscpy(version_string, version, sizeof(version_string));
 
-	strncpy(version_string, version, sizeof(version_string));
+	if (ret < 0)
+		return ret;
 
 	if (match_token(version_string, token, args) != 1)
 		return -EINVAL;
-- 
2.30.2