[PATCH 5.10 59/86] net: Fix data-races around sysctl_devconf_inherit_init_net.

Greg Kroah-Hartman
2022-08-29T11:26:41Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit a5612ca10d1aa05624ebe72633e0c8c792970833 ]

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

Fixes: 856c395cfa63 ("net: introduce a knob to control whether to inherit devconf config")
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>
---
include/linux/netdevice.h | 9 +++++++++
net/ipv4/devinet.c | 16 ++++++++++------
net/ipv6/addrconf.c | 5 ++---
3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c05701f89d6dd..6564fb4ac49e1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -643,6 +643,15 @@ static inline bool net_has_fallback_tunnels(const struct net *net)
#endif
}

+static inline int net_inherit_devconf(void)
+{
+#if IS_ENABLED(CONFIG_SYSCTL)
+ return READ_ONCE(sysctl_devconf_inherit_init_net);
+#else
+ return 0;
+#endif
+}
+
static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
{
#if defined(CONFIG_XPS) && defined(CONFIG_NUMA)
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 148ef484a66ce..8f17538755507 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2668,23 +2668,27 @@ static __net_init int devinet_init_net(struct net *net)
#endif

if (!net_eq(net, &init_net)) {
- if (IS_ENABLED(CONFIG_SYSCTL) &&
- sysctl_devconf_inherit_init_net == 3) {
+ switch (net_inherit_devconf()) {
+ case 3:
/* copy from the current netns */
memcpy(all, current->nsproxy->net_ns->ipv4.devconf_all,
sizeof(ipv4_devconf));
memcpy(dflt,
current->nsproxy->net_ns->ipv4.devconf_dflt,
sizeof(ipv4_devconf_dflt));
- } else if (!IS_ENABLED(CONFIG_SYSCTL) ||
- sysctl_devconf_inherit_init_net != 2) {
- /* inherit == 0 or 1: copy from init_net */
+ break;
+ case 0:
+ case 1:
+ /* copy from init_net */
memcpy(all, init_net.ipv4.devconf_all,
sizeof(ipv4_devconf));
memcpy(dflt, init_net.ipv4.devconf_dflt,
sizeof(ipv4_devconf_dflt));
+ break;
+ case 2:
+ /* use compiled values */
+ break;
}
- /* else inherit == 2: use compiled values */
}

#ifdef CONFIG_SYSCTL
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 05317e6f48f8a..ed1e5bfc97b31 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -7042,9 +7042,8 @@ static int __net_init addrconf_init_net(struct net *net)
if (!dflt)
goto err_alloc_dflt;

- if (IS_ENABLED(CONFIG_SYSCTL) &&
- !net_eq(net, &init_net)) {
- switch (sysctl_devconf_inherit_init_net) {
+ if (!net_eq(net, &init_net)) {
+ switch (net_inherit_devconf()) {
case 1: /* copy from init_net */
memcpy(all, init_net.ipv6.devconf_all,
sizeof(ipv6_devconf));
--
2.35.1