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authorJiri Pirko <jiri@mellanox.com>2017-09-13 17:32:37 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-12 11:51:20 +0200
commitf86d3b1a28a7271774fe4e8a9a028f6b209e1fd3 (patch)
treea3b997583020092fdd5dcbf90d213f0e461c8796 /net/sched
parentf860ca549de4670e95516d6e7cbbc733a69c63db (diff)
net: sched: fix use-after-free in tcf_action_destroy and tcf_del_walker
[ Upstream commit 255cd50f207ae8ec7b22663246c833407744e634 ] 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/sched')
-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 c651cfce9be6..f3117324146a 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -141,7 +141,7 @@ static int tcf_del_walker(struct tcf_hashinfo *hinfo, struct sk_buff *skb,
hlist_for_each_entry_safe(p, n, head, tcfa_head) {
ret = __tcf_hash_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;
@@ -450,13 +450,15 @@ 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_hash_release(a, bind, true);
if (ret == ACT_P_DELETED)
- module_put(a->ops->owner);
+ module_put(ops->owner);
else if (ret < 0)
return ret;
}