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

From: Jim Davis
Date: Thu Sep 03 2015 - 16:03:54 EST


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 âwrite_certâ:
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@krebstar:~/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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