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Commit 0cba7ca6 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Greg Kroah-Hartman
Browse files

icmp: Fix data-races around sysctl. 



[ Upstream commit 48d7ee321ea5182c6a70782aa186422a70e67e22 ]

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>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 0e41a0f7

net/ipv4/icmp.c

+3 −2
Original line number Original line Diff line number Diff line
@@ -261,11 +261,12 @@ bool icmp_global_allow(void) 
	spin_lock(&icmp_global.lock);

	spin_lock(&icmp_global.lock);

	delta = min_t(u32, now - icmp_global.stamp, HZ);

	delta = min_t(u32, now - icmp_global.stamp, HZ);

	if (delta >= HZ / 50) {

	if (delta >= HZ / 50) {

		incr = sysctl_icmp_msgs_per_sec * delta / HZ ;

		incr = READ_ONCE(sysctl_icmp_msgs_per_sec) * delta / HZ;

		if (incr)

		if (incr)

			WRITE_ONCE(icmp_global.stamp, now);

			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) {

	if (credit) {

		/* We want to use a credit of one in average, but need to randomize

		/* We want to use a credit of one in average, but need to randomize

		 * it for security reasons.

		 * it for security reasons.