linux-kernel - Compiler warning with extract-cert.c in recent linux-next builds

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Date:	Thu, 3 Sep 2015 13:03:46 -0700
From:	Jim Davis <jim.epost@...il.com>
To:	linux-next <linux-next@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, dhowells@...hat.com,
	David Woodhouse <dwmw2@...radead.org>, keyrings@...ux-nfs.org
Subject: Compiler warning with extract-cert.c in recent linux-next builds

Over the past couple of days, linux-next builds have been turning up
this compile warning

buildlog-1441309952.txt:scripts/extract-cert.c: In function ‘write_cert’:
buildlog-1441309952.txt:scripts/extract-cert.c:89:2: warning: format
not a string literal and no format arguments [-Wformat-security]
buildlog-1441309952.txt-  ERR(!i2d_X509_bio(wb, x509), cert_dst);
buildlog-1441309952.txt-  ^

This is on an Ubuntu 15.04 installation, with

jim@...bstar:~/linux-next-2$ gcc --version
gcc (Ubuntu 4.9.2-10ubuntu13) 4.9.2

Naively adding a "%s" format string silences the warning,

diff --git a/scripts/extract-cert.c b/scripts/extract-cert.c
index fd0db015c65c..907fbd888e7b 100644
--- a/scripts/extract-cert.c
+++ b/scripts/extract-cert.c
@@ -86,7 +86,7 @@ static void write_cert(X509 *x509)
         ERR(!wb, "%s", cert_dst);
     }
     X509_NAME_oneline(X509_get_subject_name(x509), buf, sizeof(buf));
-    ERR(!i2d_X509_bio(wb, x509), cert_dst);
+    ERR(!i2d_X509_bio(wb, x509), "%s",cert_dst);
     if (kbuild_verbose)
         fprintf(stderr, "Extracted cert: %s\n", buf);
 }

but I won't pretend to understand the code in detail!

-- 
Jim
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