From: Davide Caratti dcaratti@redhat.com
[ Upstream commit 78dcdffe0418ac8f3f057f26fe71ccf4d8ed851f ]
with commit e2ca070f89ec ("net: sched: protect against stack overflow in TC act_mirred"), act_mirred protected itself against excessive stack growth using per_cpu counter of nested calls to tcf_mirred_act(), and capping it to MIRRED_RECURSION_LIMIT. However, such protection does not detect recursion/loops in case the packet is enqueued to the backlog (for example, when the mirred target device has RPS or skb timestamping enabled). Change the wording from "recursion" to "nesting" to make it more clear to readers.
CC: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: Davide Caratti dcaratti@redhat.com Reviewed-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Acked-by: Jamal Hadi Salim jhs@mojatatu.com Signed-off-by: Paolo Abeni pabeni@redhat.com Stable-dep-of: ca22da2fbd69 ("act_mirred: use the backlog for nested calls to mirred ingress") Signed-off-by: Dragos-Marian Panait dragos.panait@windriver.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/act_mirred.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
--- a/net/sched/act_mirred.c +++ b/net/sched/act_mirred.c @@ -28,8 +28,8 @@ static LIST_HEAD(mirred_list); static DEFINE_SPINLOCK(mirred_list_lock);
-#define MIRRED_RECURSION_LIMIT 4 -static DEFINE_PER_CPU(unsigned int, mirred_rec_level); +#define MIRRED_NEST_LIMIT 4 +static DEFINE_PER_CPU(unsigned int, mirred_nest_level);
static bool tcf_mirred_is_act_redirect(int action) { @@ -225,7 +225,7 @@ static int tcf_mirred_act(struct sk_buff struct sk_buff *skb2 = skb; bool m_mac_header_xmit; struct net_device *dev; - unsigned int rec_level; + unsigned int nest_level; int retval, err = 0; bool use_reinsert; bool want_ingress; @@ -236,11 +236,11 @@ static int tcf_mirred_act(struct sk_buff int mac_len; bool at_nh;
- rec_level = __this_cpu_inc_return(mirred_rec_level); - if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) { + nest_level = __this_cpu_inc_return(mirred_nest_level); + if (unlikely(nest_level > MIRRED_NEST_LIMIT)) { net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n", netdev_name(skb->dev)); - __this_cpu_dec(mirred_rec_level); + __this_cpu_dec(mirred_nest_level); return TC_ACT_SHOT; }
@@ -310,7 +310,7 @@ static int tcf_mirred_act(struct sk_buff err = tcf_mirred_forward(res->ingress, skb); if (err) tcf_action_inc_overlimit_qstats(&m->common); - __this_cpu_dec(mirred_rec_level); + __this_cpu_dec(mirred_nest_level); return TC_ACT_CONSUMED; } } @@ -322,7 +322,7 @@ out: if (tcf_mirred_is_act_redirect(m_eaction)) retval = TC_ACT_SHOT; } - __this_cpu_dec(mirred_rec_level); + __this_cpu_dec(mirred_nest_level);
return retval; }