[Patch net] xt_cgroup: initialize info->priv in cgroup_mt_check_v1()

[Cong Wang]

xt_cgroup_info_v1->priv is an internal pointer only used for kernel,
we should not trust what user-space provides.

Reported-by: <syzbot+4fbcfcc0d2e6592bd...@syzkaller.appspotmail.com>
Fixes: c38c4597e4bf ("netfilter: implement xt_cgroup cgroup2 path match")
Cc: Pablo Neira Ayuso <pa...@netfilter.org>
Signed-off-by: Cong Wang <xiyou.wangc...@gmail.com>
---
 net/netfilter/xt_cgroup.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/xt_cgroup.c b/net/netfilter/xt_cgroup.c
index 1db1ce59079f..891f4e7e8ea7 100644
--- a/net/netfilter/xt_cgroup.c
+++ b/net/netfilter/xt_cgroup.c
@@ -52,6 +52,7 @@ static int cgroup_mt_check_v1(const struct xt_mtchk_param 
*par)
                return -EINVAL;
        }
 
+       info->priv = NULL;
        if (info->has_path) {
                cgrp = cgroup_get_from_path(info->path);
                if (IS_ERR(cgrp)) {
-- 
2.13.0