[PATCH 5.18 112/231] icmp: Fix a data-race around sysctl_icmp_echo_ignore_all.

Greg Kroah-Hartman
2022-07-19T12:58:55Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit bb7bb35a63b4812da8e3aff587773678e31d23e3 ]

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

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/icmp.c | 2 +-
net/ipv4/sysctl_net_ipv4.c | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 97350a38a75d..92eaa96a9ff1 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -990,7 +990,7 @@ static bool icmp_echo(struct sk_buff *skb)

net = dev_net(skb_dst(skb)->dev);
/* should there be an ICMP stat for ignored echos? */
- if (net->ipv4.sysctl_icmp_echo_ignore_all)
+ if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
return true;

icmp_param.data.icmph = *icmp_hdr(skb);
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index ad80d180b60b..8987864c4479 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -603,6 +603,8 @@ static struct ctl_table ipv4_net_table[] = {
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE
},
{
.procname = "icmp_echo_enable_probe",
--
2.35.1