netdev - [PATCH iproute2 2/5] bridge: Fix memory leak when doing 'fdb get'

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Message-Id: <20220710235254.568878-3-bpoirier@nvidia.com>
Date:   Mon, 11 Jul 2022 08:52:51 +0900
From:   Benjamin Poirier <bpoirier@...dia.com>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org, Ido Schimmel <idosch@...dia.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...il.com>
Subject: [PATCH iproute2 2/5] bridge: Fix memory leak when doing 'fdb get'

With the following command sequence:

ip link add br0 up type bridge
ip link add dummy0 up address 02:00:00:00:00:01 master br0 type dummy
bridge fdb get 02:00:00:00:00:01 br br0

when running the last command under valgrind, it reports

32,768 bytes in 1 blocks are definitely lost in loss record 2 of 2
   at 0x483F7B5: malloc (vg_replace_malloc.c:381)
   by 0x11C1EC: rtnl_recvmsg (libnetlink.c:838)
   by 0x11C4D1: __rtnl_talk_iov.constprop.0 (libnetlink.c:1040)
   by 0x11D994: __rtnl_talk (libnetlink.c:1141)
   by 0x11D994: rtnl_talk (libnetlink.c:1147)
   by 0x10D336: fdb_get (fdb.c:652)
   by 0x48907FC: (below main) (libc-start.c:332)

Free the answer obtained from rtnl_talk().

Fixes: 4ed5ad7bd3c6 ("bridge: fdb get support")
Reported-by: Ido Schimmel <idosch@...dia.com>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
Signed-off-by: Benjamin Poirier <bpoirier@...dia.com>
---
 bridge/fdb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/bridge/fdb.c b/bridge/fdb.c
index 8912f092..08f6c72b 100644
--- a/bridge/fdb.c
+++ b/bridge/fdb.c
@@ -571,6 +571,7 @@ static int fdb_get(int argc, char **argv)
 	char *addr = NULL;
 	short vlan = -1;
 	char *endptr;
+	int ret;
 
 	while (argc > 0) {
 		if ((strcmp(*argv, "brport") == 0) || strcmp(*argv, "dev") == 0) {
@@ -657,13 +658,15 @@ static int fdb_get(int argc, char **argv)
 	 * if -json was specified.
 	 */
 	new_json_obj(json);
+	ret = 0;
 	if (print_fdb(answer, stdout) < 0) {
 		fprintf(stderr, "An error :-)\n");
-		return -1;
+		ret = -1;
 	}
 	delete_json_obj();
+	free(answer);
 
-	return 0;
+	return ret;
 }
 
 int do_fdb(int argc, char **argv)
-- 
2.36.1