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authorJiri Pirko <jiri@mellanox.com>2017-09-13 17:32:37 +0200
committerDavid S. Miller <davem@davemloft.net>2017-09-13 09:34:08 -0700
commit255cd50f207ae8ec7b22663246c833407744e634 (patch)
tree8c98c50e192e780bfa9d845b4c7e416cb3ae9d3a /net
parent822f8565c93949fb2d31502d595c8bc45629c9b7 (diff)
net: sched: fix use-after-free in tcf_action_destroy and tcf_del_walker
Recent commit d7fb60b9cafb ("net_sched: get rid of tcfa_rcu") removed freeing in call_rcu, which changed already existing hard-to-hit race condition into 100% hit: [ 598.599825] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 [ 598.607782] IP: tcf_action_destroy+0xc0/0x140 Or: [ 40.858924] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030 [ 40.862840] IP: tcf_generic_walker+0x534/0x820 Fix this by storing the ops and use them directly for module_put call. Fixes: a85a970af265 ("net_sched: move tc_action into tcf_common") Signed-off-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/sched/act_api.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index fcd7dc7b807a..da6fa82c98a8 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -180,7 +180,7 @@ static int tcf_del_walker(struct tcf_idrinfo *idrinfo, struct sk_buff *skb,
idr_for_each_entry_ext(idr, p, id) {
ret = __tcf_idr_release(p, false, true);
if (ret == ACT_P_DELETED) {
- module_put(p->ops->owner);
+ module_put(ops->owner);
n_i++;
} else if (ret < 0) {
goto nla_put_failure;
@@ -514,13 +514,15 @@ EXPORT_SYMBOL(tcf_action_exec);
int tcf_action_destroy(struct list_head *actions, int bind)
{
+ const struct tc_action_ops *ops;
struct tc_action *a, *tmp;
int ret = 0;
list_for_each_entry_safe(a, tmp, actions, list) {
+ ops = a->ops;
ret = __tcf_idr_release(a, bind, true);
if (ret == ACT_P_DELETED)
- module_put(a->ops->owner);
+ module_put(ops->owner);
else if (ret < 0)
return ret;
}