diff mbox series

[v7,1/4] fs: unicode: Use strscpy() instead of strncpy()

Message ID 20210407144845.53266-2-shreeya.patel@collabora.com
State Not Applicable
Headers show
Series Make UTF-8 encoding loadable | expand

Commit Message

Shreeya Patel April 7, 2021, 2:48 p.m. UTC
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)
Acked-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
Reported-by: kernel test robot <lkp@intel.com>
---
 fs/unicode/utf8-core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Eric Biggers April 8, 2021, 12:52 a.m. UTC | #1
On Wed, Apr 07, 2021 at 08:18:42PM +0530, Shreeya Patel wrote:
> 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().

This explanation is a bit misleading.  It would be clearer to phrase this in
terms of fixing how overly-long strings are handled: start returning an error
instead of creating a non-null-terminated string.

> 
> Fixes: 9d53690f0d4e5 (unicode: implement higher level API for string handling)

There should be quotes around the commit title here.

- Eric
diff mbox series

Patch

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;