[PATCH 5.18 114/231] icmp: Fix a data-race around sysctl_icmp_echo_ignore_broadcasts.

Greg Kroah-Hartman
2022-07-19T12:59:03Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 66484bb98ed2dfa1dda37a32411483d8311ac269 ]

While reading sysctl_icmp_echo_ignore_broadcasts, 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 7edc8a3b1646..2c402b4671a1 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -1239,7 +1239,7 @@ int icmp_rcv(struct sk_buff *skb)
*/
if ((icmph->type == ICMP_ECHO ||
icmph->type == ICMP_TIMESTAMP) &&
- net->ipv4.sysctl_icmp_echo_ignore_broadcasts) {
+ READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_broadcasts)) {
goto error;
}
if (icmph->type != ICMP_ECHO &&
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 8987864c4479..6613351094ce 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -621,6 +621,8 @@ 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_ignore_bogus_error_responses",
--
2.35.1