[PATCH 6.8 223/336] ipv6: annotate data-races around cnf.disable_ipv6

Greg Kroah-Hartman
2024-05-14T10:44:31Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit d289ab65b89c1d4d88417cb6c03e923f21f95fae ]

disable_ipv6 is read locklessly, add appropriate READ_ONCE()
and WRITE_ONCE() annotations.

v2: do not preload net before rtnl_trylock() in
addrconf_disable_ipv6() (Jiri)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 4db783d68b9b ("ipv6: prevent NULL dereference in ip6_output()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv6/addrconf.c | 9 +++++----
net/ipv6/ip6_input.c | 4 ++--
net/ipv6/ip6_output.c | 2 +-
3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 775f51cbc539b..c4e2f9d35e687 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4164,7 +4164,7 @@ static void addrconf_dad_work(struct work_struct *w)
if (!ipv6_generate_eui64(addr.s6_addr + 8, idev->dev) &&
ipv6_addr_equal(&ifp->addr, &addr)) {
/* DAD failed for link-local based on MAC */
- idev->cnf.disable_ipv6 = 1;
+ WRITE_ONCE(idev->cnf.disable_ipv6, 1);

pr_info("%s: IPv6 being disabled!\n",
ifp->idev->dev->name);
@@ -6325,7 +6325,8 @@ static void addrconf_disable_change(struct net *net, __s32 newf)
idev = __in6_dev_get(dev);
if (idev) {
int changed = (!idev->cnf.disable_ipv6) ^ (!newf);
- idev->cnf.disable_ipv6 = newf;
+
+ WRITE_ONCE(idev->cnf.disable_ipv6, newf);
if (changed)
dev_disable_change(idev);
}
@@ -6342,7 +6343,7 @@ static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int newf)

net = (struct net *)table->extra2;
old = *p;
- *p = newf;
+ WRITE_ONCE(*p, newf);

if (p == &net->ipv6.devconf_dflt->disable_ipv6) {
rtnl_unlock();
@@ -6350,7 +6351,7 @@ static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int newf)
}

if (p == &net->ipv6.devconf_all->disable_ipv6) {
- net->ipv6.devconf_dflt->disable_ipv6 = newf;
+ WRITE_ONCE(net->ipv6.devconf_dflt->disable_ipv6, newf);
addrconf_disable_change(net, newf);
} else if ((!newf) ^ (!old))
dev_disable_change((struct inet6_dev *)table->extra1);
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index b8378814532ce..1ba97933c74fb 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -168,9 +168,9 @@ static struct sk_buff *ip6_rcv_core(struct sk_buff *skb, struct net_device *dev,

SKB_DR_SET(reason, NOT_SPECIFIED);
if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
- !idev || unlikely(idev->cnf.disable_ipv6)) {
+ !idev || unlikely(READ_ONCE(idev->cnf.disable_ipv6))) {
__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
- if (idev && unlikely(idev->cnf.disable_ipv6))
+ if (idev && unlikely(READ_ONCE(idev->cnf.disable_ipv6)))
SKB_DR_SET(reason, IPV6DISABLED);
goto drop;
}
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 568065a015c41..e4b02e94c2eb3 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -234,7 +234,7 @@ int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
skb->protocol = htons(ETH_P_IPV6);
skb->dev = dev;

- if (unlikely(idev->cnf.disable_ipv6)) {
+ if (unlikely(READ_ONCE(idev->cnf.disable_ipv6))) {
IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
kfree_skb_reason(skb, SKB_DROP_REASON_IPV6DISABLED);
return 0;
--
2.43.0