diff mbox series

[SRU,Focal,v2,5/6] net/sched: act_mirred: better wording on protection against excessive stack growth

Message ID 20230512180139.27507-8-yuxuan.luo@canonical.com
State New
Headers show
Series [SRU,Focal,v2,1/6] net: sched: extract qstats update code into functions | expand

Commit Message

Yuxuan Luo May 12, 2023, 6:01 p.m. UTC 
From: Davide Caratti <dcaratti@redhat.com>

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>
(cherry picked from commit 78dcdffe0418ac8f3f057f26fe71ccf4d8ed851f)
CVE-2022-4269
Signed-off-by: Yuxuan Luo <yuxuan.luo@canonical.com>
---
 net/sched/act_mirred.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)
diff mbox series

Patch

diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index a523a67268178..1f2187c929304 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 @@  static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 	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 *skb, const struct tc_action *a,
 	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;
 	}
 
@@ -309,7 +309,7 @@  static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 			err = tcf_mirred_forward(want_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;
 		}
 	}
@@ -321,7 +321,7 @@  static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
 		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;
 }