[PATCH 5.10 58/86] net: Fix data-races around sysctl_fb_tunnels_only_for_init_net.

Greg Kroah-Hartman
2022-08-29T11:20:09Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit af67508ea6cbf0e4ea27f8120056fa2efce127dd ]

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

Fixes: 79134e6ce2c9 ("net: do not create fallback tunnels for non-default namespaces")
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 | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ed2d531400051..c05701f89d6dd 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -633,9 +633,14 @@ extern int sysctl_devconf_inherit_init_net;
*/
static inline bool net_has_fallback_tunnels(const struct net *net)
{
- return !IS_ENABLED(CONFIG_SYSCTL) ||
- !sysctl_fb_tunnels_only_for_init_net ||
- (net == &init_net && sysctl_fb_tunnels_only_for_init_net == 1);
+#if IS_ENABLED(CONFIG_SYSCTL)
+ int fb_tunnels_only_for_init_net = READ_ONCE(sysctl_fb_tunnels_only_for_init_net);
+
+ return !fb_tunnels_only_for_init_net ||
+ (net_eq(net, &init_net) && fb_tunnels_only_for_init_net == 1);
+#else
+ return true;
+#endif
}

static inline int netdev_queue_numa_node_read(const struct netdev_queue *q)
--
2.35.1