netdev - [PATCH net v2] rps: Correct wrong skb_flow

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1525990182-12042-1-git-send-email-gfree.wind@vip.163.com>
Date:   Fri, 11 May 2018 06:09:42 +0800
From:   gfree.wind@....163.com
To:     davem@...emloft.net, daniel@...earbox.net, edumazet@...gle.com,
        willemb@...gle.com, jakub.kicinski@...ronome.com,
        ktkhai@...tuozzo.com, ast@...nel.org, linux@...musvillemoes.dk,
        john.fastabend@...il.com, brouer@...hat.com, dsahern@...il.com,
        netdev@...r.kernel.org
Cc:     Gao Feng <gfree.wind@....163.com>
Subject: [PATCH net v2] rps: Correct wrong skb_flow_limit check when enable RPS

From: Gao Feng <gfree.wind@....163.com>

The skb flow limit is implemented for each CPU independently. In the
current codes, the function skb_flow_limit gets the softnet_data by
this_cpu_ptr. But the target cpu of enqueue_to_backlog would be not
the current cpu when enable RPS. As the result, the skb_flow_limit checks
the stats of current CPU, while the skb is going to append the queue of
another CPU. It isn't the expected behavior.

Now pass the softnet_data as a param to make consistent.

Fixes: 99bbc7074190 ("rps: selective flow shedding during softnet overflow")
Signed-off-by: Gao Feng <gfree.wind@....163.com>
---
 v2: Add Fixes tag per Eric, and enhance the commit log
 v1: intial version

 net/core/dev.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index af0558b..0f98eff 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3883,18 +3883,15 @@ static int rps_ipi_queued(struct softnet_data *sd)
 int netdev_flow_limit_table_len __read_mostly = (1 << 12);
 #endif
 
-static bool skb_flow_limit(struct sk_buff *skb, unsigned int qlen)
+static bool skb_flow_limit(struct softnet_data *sd, struct sk_buff *skb, unsigned int qlen)
 {
 #ifdef CONFIG_NET_FLOW_LIMIT
 	struct sd_flow_limit *fl;
-	struct softnet_data *sd;
 	unsigned int old_flow, new_flow;
 
 	if (qlen < (netdev_max_backlog >> 1))
 		return false;
 
-	sd = this_cpu_ptr(&softnet_data);
-
 	rcu_read_lock();
 	fl = rcu_dereference(sd->flow_limit);
 	if (fl) {
@@ -3938,7 +3935,7 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
 	if (!netif_running(skb->dev))
 		goto drop;
 	qlen = skb_queue_len(&sd->input_pkt_queue);
-	if (qlen <= netdev_max_backlog && !skb_flow_limit(skb, qlen)) {
+	if (qlen <= netdev_max_backlog && !skb_flow_limit(sd, skb, qlen)) {
 		if (qlen) {
 enqueue:
 			__skb_queue_tail(&sd->input_pkt_queue, skb);
-- 
1.9.1