Commit 9608fa65 authored Dec 03, 2020 by Davide Caratti Committed by Jakub Kicinski Dec 03, 2020

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 dereferencing 4 bytes at mpls_hdr(): ensure that the label is
contained in the skb "linear" area.

Found by code inspection.

v2:
 - use MPLS_HLEN instead of sizeof(new_lse), thanks to Jakub Kicinski

Fixes: 2a2ea508 ("net: sched: add mpls manipulation actions to TC")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Link: https://lore.kernel.org/r/3243506cba43d14858f3bd21ee0994160e44d64a.1606987058.git.dcaratti@redhat.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 43c13605

net/sched/act_mpls.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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) + MPLS_HLEN))
		goto drop;
		new_lse = tcf_mpls_get_lse(mpls_hdr(skb), p, false);
		if (skb_mpls_update_lse(skb, new_lse))
		goto drop;

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