linux-kernel - [PATCH 5.4 27/71] net: Fix data-races around sysctl

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Message-Id: <20220719114554.924609762@linuxfoundation.org>
Date:   Tue, 19 Jul 2022 13:53:50 +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 5.4 27/71] net: Fix data-races around sysctl_mem.

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

[ Upstream commit 310731e2f1611d1d13aae237abcf8e66d33345d5 ]

While reading .sysctl_mem, it can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
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>
---
 include/net/sock.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 7f213cfcb3cc..9d687070d272 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1400,7 +1400,7 @@ void __sk_mem_reclaim(struct sock *sk, int amount);
 /* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */
 static inline long sk_prot_mem_limits(const struct sock *sk, int index)
 {
-	long val = sk->sk_prot->sysctl_mem[index];
+	long val = READ_ONCE(sk->sk_prot->sysctl_mem[index]);
 
 #if PAGE_SIZE > SK_MEM_QUANTUM
 	val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;
-- 
2.35.1