From: Davide Caratti Date: Thu, 3 Dec 2020 09:37:52 +0000 (+0100) Subject: net/sched: act_mpls: ensure LSE is pullable before reading it X-Git-Tag: v5.9.13~12 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bcfeff6ec630b3837c67730675e8e343d73b48cc;p=thirdparty%2Fkernel%2Fstable.git net/sched: act_mpls: ensure LSE is pullable before reading it [ Upstream commit 9608fa653059c3f72faab0c148ac8773c46e7314 ] 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: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC") Signed-off-by: Davide Caratti Acked-by: Guillaume Nault Link: https://lore.kernel.org/r/3243506cba43d14858f3bd21ee0994160e44d64a.1606987058.git.dcaratti@redhat.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/sched/act_mpls.c b/net/sched/act_mpls.c index ca026e2bf8d27..2701017a3a04d 100644 --- a/net/sched/act_mpls.c +++ b/net/sched/act_mpls.c @@ -88,6 +88,9 @@ 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;