net/sched: act_mirred: better wording on protection against excessive stack growth
[ 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.
BUG=b/261837988
RELEASE_NOTE=Fixed CVE-2022-4269 in the Linux kernel.
CC: Jamal Hadi Salim <jhs@mojatatu.com>
Change-Id: Iee4aeebf89631d0d70bf1ace2dc45eaab48e5417
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>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/50523
Reviewed-by: Meena Shanmugam <meenashanmugam@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 53594b046..01a44c3 100644
--- 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 @@
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 @@
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 @@
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 @@
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;
}
