[PATCH 5.9 35/46] net/sched: act_mpls: ensure LSE is pullable before reading it
From: Greg Kroah-Hartman
Date: Sun Dec 06 2020 - 06:45:04 EST
From: Davide Caratti <dcaratti@xxxxxxxxxx>
[ 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 <dcaratti@xxxxxxxxxx>
Acked-by: Guillaume Nault <gnault@xxxxxxxxxx>
Link: https://lore.kernel.org/r/3243506cba43d14858f3bd21ee0994160e44d64a.1606987058.git.dcaratti@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/act_mpls.c | 3 +++
1 file changed, 3 insertions(+)
--- a/net/sched/act_mpls.c
+++ b/net/sched/act_mpls.c
@@ -88,6 +88,9 @@ static int tcf_mpls_act(struct sk_buff *
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;