This is a note to let you know that I've just added the patch titled
net: sched: fix use-after-free in tcf_action_destroy and tcf_del_walker
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-fix-use-after-free-in-tcf_action_destroy-and-tcf_del_walker.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Oct 10 16:09:22 CEST 2017
From: Jiri Pirko <jiri@xxxxxxxxxxxx>
Date: Wed, 13 Sep 2017 17:32:37 +0200
Subject: net: sched: fix use-after-free in tcf_action_destroy and tcf_del_walker
From: Jiri Pirko <jiri@xxxxxxxxxxxx>
[ 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@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/act_api.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -141,7 +141,7 @@ static int tcf_del_walker(struct tcf_has
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;
}
Patches currently in stable-queue which might be from jiri@xxxxxxxxxxxx are
queue-4.9/net-sched-fix-use-after-free-in-tcf_action_destroy-and-tcf_del_walker.patch
queue-4.9/mlxsw-spectrum-prevent-mirred-related-crash-on-removal.patch