netdev - [PATCH net] net/sched: act_mpls: ensure LSE is pullable before reading it

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <e14a44135817430fc69b3c624895f8584a560975.1605716949.git.dcaratti@redhat.com>
Date:   Wed, 18 Nov 2020 17:36:52 +0100
From:   Davide Caratti <dcaratti@...hat.com>
To:     Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org,
        Jakub Kicinski <kuba@...nel.org>
Cc:     gnault@...hat.com, marcelo.leitner@...il.com
Subject: [PATCH net] net/sched: act_mpls: ensure LSE is pullable before reading it

when 'act_mpls' is used to mangle the LSE, the current value is read from
the packet with mpls_hdr(): ensure that the label is contained in the skb
"linear" area.

Found by code inspection.

Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC")
Signed-off-by: Davide Caratti <dcaratti@...hat.com>
---
 net/sched/act_mpls.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c
index 5c7456e5b5cf..03138ad59e9b 100644
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -105,6 +105,9 @@ static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
 			goto drop;
 		break;
 	case TCA_MPLS_ACT_MODIFY:
+		if (!pskb_may_pull(skb,
+				   skb_network_offset(skb) + sizeof(new_lse)))
+			goto drop;
 		new_lse = tcf_mpls_get_lse(mpls_hdr(skb), p, false);
 		if (skb_mpls_update_lse(skb, new_lse))
 			goto drop;
-- 
2.28.0