netdev - [PATCH v2 net 09/12] net: Fix data-races around sysctl

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Message-ID: <20220706234003.66760-10-kuniyu@amazon.com>
Date:   Wed, 6 Jul 2022 16:40:00 -0700
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>
CC:     Kuniyuki Iwashima <kuniyu@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 net 09/12] net: Fix data-races around sysctl_mem.

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>
---
 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 72ca97ccb460..9fa54762e077 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1529,7 +1529,7 @@ 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;
-- 
2.30.2