diff options
| author | Roman Kapl <code@rkapl.cz> | 2017-11-20 22:21:13 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-11-24 01:25:37 +0900 |
| commit | d7aa04a5e82b4f254d306926c81eae8df69e5200 (patch) | |
| tree | 58ef4949cc32041b00d14eeaa0aef4587331a45e | |
| parent | 0cc03504c9f1b9c9da819094db37507c69ee9145 (diff) | |
net: sched: fix crash when deleting secondary chains
If you flush (delete) a filter chain other than chain 0 (such as when
deleting the device), the kernel may run into a use-after-free. The
chain refcount must not be decremented unless we are sure we are done
with the chain.
To reproduce the bug, run:
ip link add dtest type dummy
tc qdisc add dev dtest ingress
tc filter add dev dtest chain 1 parent ffff: flower
ip link del dtest
Introduced in: commit f93e1cdcf42c ("net/sched: fix filter flushing"),
but unless you have KAsan or luck, you won't notice it until
commit 0dadc117ac8b ("cls_flower: use tcf_exts_get_net() before call_rcu()")
Fixes: f93e1cdcf42c ("net/sched: fix filter flushing")
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Roman Kapl <code@rkapl.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/sched/cls_api.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index ab255b421781..7d97f612c9b9 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -205,13 +205,14 @@ static void tcf_chain_head_change(struct tcf_chain *chain, static void tcf_chain_flush(struct tcf_chain *chain) { - struct tcf_proto *tp; + struct tcf_proto *tp = rtnl_dereference(chain->filter_chain); tcf_chain_head_change(chain, NULL); - while ((tp = rtnl_dereference(chain->filter_chain)) != NULL) { + while (tp) { RCU_INIT_POINTER(chain->filter_chain, tp->next); - tcf_chain_put(chain); tcf_proto_destroy(tp); + tp = rtnl_dereference(chain->filter_chain); + tcf_chain_put(chain); } } |