From: Jakub Kicinski <kuba@xxxxxxxxxx>
[ Upstream commit 166c2c8a6a4dc2e4ceba9e10cfe81c3e469e3210 ]
If we're redirecting the skb, and haven't called tcf_mirred_forward(),
yet, we need to tell the core to drop the skb by setting the retcode
to SHOT. If we have called tcf_mirred_forward(), however, the skb
is out of our hands and returning SHOT will lead to UaF.
Move the retval override to the error path which actually need it.
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@xxxxxxxxxxxxxxx>
Fixes: e5cf1baf92cb ("act_mirred: use TC_ACT_REINSERT when possible")
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@xxxxxxxxxxxxx>
Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
---
Verified the build test
---
net/sched/act_mirred.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 36395e5db3b4..24c70ba6eebc 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -259,13 +259,13 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
dev = rcu_dereference_bh(m->tcfm_dev);
if (unlikely(!dev)) {
pr_notice_once("tc mirred: target device is gone\n");
- goto out;
+ goto err_cant_do;
}
if (unlikely(!(dev->flags & IFF_UP)) || !netif_carrier_ok(dev)) {
net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
dev->name);
- goto out;
+ goto err_cant_do;
}
/* we could easily avoid the clone only if called by ingress and clsact;
@@ -279,7 +279,7 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
if (!use_reinsert) {
skb2 = skb_clone(skb, GFP_ATOMIC);
if (!skb2)
- goto out;
+ goto err_cant_do;
}
want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
@@ -321,12 +321,16 @@ static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
}
err = tcf_mirred_forward(want_ingress, skb2);
- if (err) {
-out:
+ if (err)
tcf_action_inc_overlimit_qstats(&m->common);
- if (tcf_mirred_is_act_redirect(m_eaction))
- retval = TC_ACT_SHOT;
- }
+ __this_cpu_dec(mirred_nest_level);
+
+ return retval;
+
+err_cant_do:
+ if (tcf_mirred_is_act_redirect(m_eaction))
+ retval = TC_ACT_SHOT;
+ tcf_action_inc_overlimit_qstats(&m->common);
__this_cpu_dec(mirred_nest_level);
return retval;
--
2.25.1
