From 27594ec4b6a7035450ba43624d1648cbd2c0aaea Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 8 Oct 2018 06:22:34 -0400 Subject: [PATCH] net: sched: cls_u32: disallow linking to root hnode Operation makes no sense. Nothing will actually break if we do so (depth limit in u32_classify() will prevent infinite loops), but according to maintainers it's best prohibited outright. NOTE: doing so guarantees that u32_destroy() will trigger the call of u32_destroy_hnode(); we might want to make that unconditional. Test: tc qdisc add dev eth0 ingress tc filter add dev eth0 parent ffff: protocol ip prio 100 u32 \ link 800: offset at 0 mask 0f00 shift 6 plus 0 eat match ip protocol 6 ff should fail with Error: cls_u32: Not linking to root node Signed-off-by: Al Viro Signed-off-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- net/sched/cls_u32.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 622f4657da94..3357331a80a2 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -797,6 +797,10 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp, NL_SET_ERR_MSG_MOD(extack, "Link hash table not found"); return -EINVAL; } + if (ht_down->is_root) { + NL_SET_ERR_MSG_MOD(extack, "Not linking to root node"); + return -EINVAL; + } ht_down->refcnt++; } -- GitLab