From c5433c4b7a57d380f4cb351316f5ba5ebae9538e Mon Sep 17 00:00:00 2001
From: Benjamin Poirier <bpoirier@nvidia.com>
Date: Mon, 11 Jul 2022 08:52:54 +0900
Subject: [PATCH] ip neigh: Fix memory leak when doing 'get'

With the following command sequence:

ip link add dummy0 type dummy
ip neigh add 192.168.0.1 dev dummy0
ip neigh get 192.168.0.1 dev dummy0

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 0x17A0EC: rtnl_recvmsg (libnetlink.c:838)
   by 0x17A3D1: __rtnl_talk_iov.constprop.0 (libnetlink.c:1040)
   by 0x17B894: __rtnl_talk (libnetlink.c:1141)
   by 0x17B894: rtnl_talk (libnetlink.c:1147)
   by 0x12E49B: ipneigh_get (ipneigh.c:728)
   by 0x1174CB: do_cmd (ip.c:136)
   by 0x116F7C: main (ip.c:324)

Free the answer obtained from rtnl_talk().

Fixes: 62842362370b ("ipneigh: neigh get support")
Suggested-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Conflict: NA
Reference: https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/commit?id=c5433c4b
---
 ip/ipneigh.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ip/ipneigh.c b/ip/ipneigh.c
index 7facc399..61b0a4a2 100644
--- a/ip/ipneigh.c
+++ b/ip/ipneigh.c
@@ -731,8 +731,10 @@ static int ipneigh_get(int argc, char **argv)
 	ipneigh_reset_filter(0);
 	if (print_neigh(answer, stdout) < 0) {
 		fprintf(stderr, "An error :-)\n");
+		free(answer);
 		return -1;
 	}
+	free(answer);
 
 	return 0;
 }
-- 
2.23.0