Commit ef299cc3 authored by Cong Wang's avatar Cong Wang Committed by David S. Miller

net_sched: cls_route: remove the right filter from hashtable

route4_change() allocates a new filter and copies values from
the old one. After the new filter is inserted into the hash
table, the old filter should be removed and freed, as the final
step of the update.

However, the current code mistakenly removes the new one. This
looks apparently wrong to me, and it causes double "free" and
use-after-free too, as reported by syzbot.

Reported-and-tested-by: syzbot+f9b32aaacd60305d9687@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+2f8c233f131943d6056d@syzkaller.appspotmail.com
Reported-and-tested-by: syzbot+9c2df9fd5e9445b74e01@syzkaller.appspotmail.com
Fixes: 1109c005 ("net: sched: RCU cls_route")
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4ae649e8
...@@ -534,8 +534,8 @@ static int route4_change(struct net *net, struct sk_buff *in_skb, ...@@ -534,8 +534,8 @@ static int route4_change(struct net *net, struct sk_buff *in_skb,
fp = &b->ht[h]; fp = &b->ht[h];
for (pfp = rtnl_dereference(*fp); pfp; for (pfp = rtnl_dereference(*fp); pfp;
fp = &pfp->next, pfp = rtnl_dereference(*fp)) { fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
if (pfp == f) { if (pfp == fold) {
*fp = f->next; rcu_assign_pointer(*fp, fold->next);
break; break;
} }
} }
......
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