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Subject[PATCH v1 net 04/15] icmp: Fix a data-race around sysctl_icmp_echo_ignore_all.
Date
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>
---
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 0f9e61d29f73..1df4aae310e0 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 cd448cdd3b38..64682a01914a 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",
--
2.30.2
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