From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Tue, 12 Jul 2022 00:15:22 +0000 (-0700)
Subject: icmp: Fix a data-race around sysctl_icmp_echo_ignore_all.
X-Git-Tag: v5.19-rc7~31^2~17^2~11
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=bb7bb35a63b4812da8e3aff587773678e31d23e3;p=users%2Fdwmw2%2Flinux.git

icmp: Fix a data-race around sysctl_icmp_echo_ignore_all.

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>
---

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 0f9e61d29f73a..1df4aae310e02 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -993,7 +993,7 @@ static enum skb_drop_reason 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 SKB_NOT_DROPPED_YET;
 
 	icmp_param.data.icmph	   = *icmp_hdr(skb);
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index cd448cdd3b381..64682a01914ab 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -599,6 +599,8 @@ 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",