linux-kernel - [PATCH 4.19 17/48] icmp: Fix data-races around sysctl.

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Message-Id: <20220719114521.333068238@linuxfoundation.org>
Date:   Tue, 19 Jul 2022 13:53:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kuniyuki Iwashima <kuniyu@...zon.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 17/48] icmp: Fix data-races around sysctl.

From: Kuniyuki Iwashima <kuniyu@...zon.com>

[ 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: 4cdf507d5452 ("icmp: add a global rate limitation")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/ipv4/icmp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index fe10a565b7d8..953cc70851cf 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -266,11 +266,12 @@ 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.
-- 
2.35.1