netdev - [iproute PATCH 1/9] tc: m_xt: Prevent segfault with standard targets

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Message-Id: <1465558928-19657-2-git-send-email-phil@nwl.cc>
Date:	Fri, 10 Jun 2016 13:42:00 +0200
From:	Phil Sutter <phil@....cc>
To:	Stephen Hemminger <shemming@...cade.com>
Cc:	netdev@...r.kernel.org
Subject: [iproute PATCH 1/9] 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@....cc>
---
 tc/m_xt.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tc/m_xt.c b/tc/m_xt.c
index c3f866df14749..62ec6d7f18e73 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) {
-- 
2.8.2