[PATCH 5.4 16/87] ip: Fix data-races around sysctl_ip_no_pmtu_disc.

Greg Kroah-Hartman
2022-07-27T16:41:50Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 0968d2a441bf6afb551fd99e60fa65ed67068963 ]

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

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/ipv4/af_inet.c | 2 +-
net/ipv4/icmp.c | 2 +-
net/ipv6/af_inet6.c | 2 +-
net/xfrm/xfrm_state.c | 2 +-
4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 9ab73fcc7411..06153386776d 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -337,7 +337,7 @@ static int inet_create(struct net *net, struct socket *sock, int protocol,
inet->hdrincl = 1;
}

- if (net->ipv4.sysctl_ip_no_pmtu_disc)
+ if (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc))
inet->pmtudisc = IP_PMTUDISC_DONT;
else
inet->pmtudisc = IP_PMTUDISC_WANT;
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 9bc01411be4c..b44f51e404ae 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -886,7 +886,7 @@ static bool icmp_unreach(struct sk_buff *skb)
* values please see
* Documentation/networking/ip-sysctl.txt
*/
- switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
+ switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
default:
net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
&iph->daddr);
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 942da168f18f..56f396ecc26b 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -222,7 +222,7 @@ static int inet6_create(struct net *net, struct socket *sock, int protocol,
inet->mc_list = NULL;
inet->rcv_tos = 0;

- if (net->ipv4.sysctl_ip_no_pmtu_disc)
+ if (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc))
inet->pmtudisc = IP_PMTUDISC_DONT;
else
inet->pmtudisc = IP_PMTUDISC_WANT;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 268bba29bb60..bee1a8143d75 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2488,7 +2488,7 @@ int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload)
int err;

if (family == AF_INET &&
- xs_net(x)->ipv4.sysctl_ip_no_pmtu_disc)
+ READ_ONCE(xs_net(x)->ipv4.sysctl_ip_no_pmtu_disc))
x->props.flags |= XFRM_STATE_NOPMTUDISC;

err = -EPROTONOSUPPORT;
--
2.35.1