netdev - [PATCH net 2/4] net/sched: act_police: disallow 'goto chain' on fallback control action

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Message-Id: <c2f076b0758b8cd997574b45c2abe064e28aca74.1540070509.git.dcaratti@redhat.com>
Date:   Sat, 20 Oct 2018 23:33:08 +0200
From:   Davide Caratti <dcaratti@...hat.com>
To:     Jiri Pirko <jiri@...nulli.us>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: [PATCH net 2/4] net/sched: act_police: disallow 'goto chain' on fallback control action

in the following command:

 # tc action add action police rate <r> burst <b> conform-exceed <c1>/<c2>

'goto chain x' is allowed only for c1: setting it for c2 makes the kernel
crash with NULL pointer dereference, since TC core doesn't initialize the
chain handle.

Signed-off-by: Davide Caratti <dcaratti@...hat.com>
---
 net/sched/act_police.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/sched/act_police.c b/net/sched/act_police.c
index 5d8bfa878477..3b793393efd1 100644
--- a/net/sched/act_police.c
+++ b/net/sched/act_police.c
@@ -150,6 +150,16 @@ static int tcf_police_init(struct net *net, struct nlattr *nla,
 		goto failure;
 	}
 
+	if (tb[TCA_POLICE_RESULT]) {
+		police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
+		if (TC_ACT_EXT_CMP(police->tcfp_result, TC_ACT_GOTO_CHAIN)) {
+			NL_SET_ERR_MSG(extack,
+				       "goto chain not allowed on fallback");
+			err = -EINVAL;
+			goto failure;
+		}
+	}
+
 	spin_lock_bh(&police->tcf_lock);
 	/* No failure allowed after this point */
 	police->tcfp_mtu = parm->mtu;
@@ -173,8 +183,6 @@ static int tcf_police_init(struct net *net, struct nlattr *nla,
 		police->peak_present = false;
 	}
 
-	if (tb[TCA_POLICE_RESULT])
-		police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
 	police->tcfp_burst = PSCHED_TICKS2NS(parm->burst);
 	police->tcfp_toks = police->tcfp_burst;
 	if (police->peak_present) {
-- 
2.17.1