From: Phil Sutter <phil@nwl.cc>
Date: Fri, 10 Jun 2016 11:42:00 +0000 (+0200)
Subject: tc: m_xt: Prevent segfault with standard targets
X-Git-Tag: v4.7.0~84
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=445745221a21ecb4111c19cfa7f4c2cf4796337f;p=thirdparty%2Fiproute2.git

tc: m_xt: Prevent segfault with standard targets

Iptables standard targets like DROP or REJECT don't implement the print
callback in libxtables. Hence the following command would segfault:

| tc filter add dev d0 parent ffff: u32 match u32 0 0 action xt -j DROP

With this patch standard targets still can't be used (and are not really
useful anyway), but at least it doesn't crash anymore.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---

diff --git a/tc/m_xt.c b/tc/m_xt.c
index c3f866df1..62ec6d7f1 100644
--- a/tc/m_xt.c
+++ b/tc/m_xt.c
@@ -250,8 +250,12 @@ static int parse_ipt(struct action_util *a, int *argc_p,
 	fprintf(stdout, "tablename: %s hook: %s\n ", tname, ipthooks[hook]);
 	fprintf(stdout, "\ttarget: ");
 
-	if (m)
-		m->print(NULL, m->t, 0);
+	if (m) {
+		if (m->print)
+			m->print(NULL, m->t, 0);
+		else
+			printf("%s ", m->name);
+	}
 	fprintf(stdout, " index %d\n", index);
 
 	if (strlen(tname) > 16) {