[PATCH 5.10 47/86] net: Fix data-races around weight_p and dev_weight_[rt]x_bias.

Greg Kroah-Hartman
2022-08-29T11:15:11Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit bf955b5ab8f6f7b0632cdef8e36b14e4f6e77829 ]

While reading weight_p, it can be changed concurrently. Thus, we need
to add READ_ONCE() to its reader.

Also, dev_[rt]x_weight can be read/written at the same time. So, we
need to use READ_ONCE() and WRITE_ONCE() for its access. Moreover, to
use the same weight_p while changing dev_[rt]x_weight, we add a mutex
in proc_do_dev_weight().

Fixes: 3d48b53fb2ae ("net: dev_weight: TX/RX orthogonality")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/dev.c | 2 +-
net/core/sysctl_net_core.c | 15 +++++++++------
net/sched/sch_generic.c | 2 +-
3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 637bc576fbd26..701a1afc91ff1 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6371,7 +6371,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
net_rps_action_and_irq_enable(sd);
}

- napi->weight = dev_rx_weight;
+ napi->weight = READ_ONCE(dev_rx_weight);
while (again) {
struct sk_buff *skb;

diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 2e0a4378e778a..0dfe9f255ab3a 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -235,14 +235,17 @@ static int set_default_qdisc(struct ctl_table *table, int write,
static int proc_do_dev_weight(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
- int ret;
+ static DEFINE_MUTEX(dev_weight_mutex);
+ int ret, weight;

+ mutex_lock(&dev_weight_mutex);
ret = proc_dointvec(table, write, buffer, lenp, ppos);
- if (ret != 0)
- return ret;
-
- dev_rx_weight = weight_p * dev_weight_rx_bias;
- dev_tx_weight = weight_p * dev_weight_tx_bias;
+ if (!ret && write) {
+ weight = READ_ONCE(weight_p);
+ WRITE_ONCE(dev_rx_weight, weight * dev_weight_rx_bias);
+ WRITE_ONCE(dev_tx_weight, weight * dev_weight_tx_bias);
+ }
+ mutex_unlock(&dev_weight_mutex);

return ret;
}
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 5d5391adb667c..68f1e89430b3b 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -403,7 +403,7 @@ static inline bool qdisc_restart(struct Qdisc *q, int *packets)

void __qdisc_run(struct Qdisc *q)
{
- int quota = dev_tx_weight;
+ int quota = READ_ONCE(dev_tx_weight);
int packets;

while (qdisc_restart(q, &packets)) {
--
2.35.1