From 06867c371958773e39b4ccac07cfe3e2fff2ea55 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Thu, 1 Mar 2018 10:35:12 +0100 Subject: [PATCH] ip-link: Fix use after free in nl_get_ll_addr_len() Immediately after freeing the buffer returned from rtnl_talk(), it is accessed again via pointer in struct rtattr array. This leads to some builds not allowing to set an interface's MAC address because the expected length value is garbage. Fixes: 86bf43c7c2fdc ("lib/libnetlink: update rtnl_talk to support malloc buff at run time") Signed-off-by: Phil Sutter --- ip/iplink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/ip/iplink.c b/ip/iplink.c index 230f4c53..d401311b 100644 --- a/ip/iplink.c +++ b/ip/iplink.c @@ -276,8 +276,9 @@ static int nl_get_ll_addr_len(unsigned int dev_index) return -1; } + len = RTA_PAYLOAD(tb[IFLA_ADDRESS]); free(answer); - return RTA_PAYLOAD(tb[IFLA_ADDRESS]); + return len; } static void iplink_parse_vf_vlan_info(int vf, int *argcp, char ***argvp,