Commit 48d7ee32 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

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: 4cdf507d ("icmp: add a global rate limitation")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dd44f04b

net/ipv4/icmp.c

+3 −2
Original line number Diff line number Diff line
@@ -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.