icmp: Fix data-races around sysctl.

While reading icmp sysctl variables, they can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 4cdf507d5452 ("icmp: add a global rate limitation")
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 efea0e7..0f9e61d 100644 (file)
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -253,11 +253,12 @@ bool icmp_global_allow(void)
        spin_lock(&icmp_global.lock);
        delta = min_t(u32, now - icmp_global.stamp, HZ);
        if (delta >= HZ / 50) {
-               incr = sysctl_icmp_msgs_per_sec * delta / HZ ;
+               incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;
                if (incr)
                        WRITE_ONCE(icmp_global.stamp, now);
        }
-       credit = min_t(u32, icmp_global.credit + incr, sysctl_icmp_msgs_burst);
+       credit = min_t(u32, icmp_global.credit + incr,
+                      READ_ONCE(sysctl_icmp_msgs_burst));
        if (credit) {
                /* We want to use a credit of one in average, but need to randomize
                 * it for security reasons.