netdev - [PATCH net] net: prevent load/store tearing on sk->sk

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Message-Id: <20191105053843.181176-1-edumazet@google.com>
Date:   Mon,  4 Nov 2019 21:38:43 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Deepa Dinamani <deepa.kernel@...il.com>
Subject: [PATCH net] net: prevent load/store tearing on sk->sk_stamp

Add a couple of READ_ONCE() and WRITE_ONCE() to prevent
load-tearing and store-tearing in sock_read_timestamp()
and sock_write_timestamp()

This might prevent another KCSAN report.

Fixes: 3a0ed3e96197 ("sock: Make sock->sk_stamp thread-safe")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Deepa Dinamani <deepa.kernel@...il.com>
---
 include/net/sock.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 8f9adcfac41bea7e46062851a25c042261323679..718e62fbe869db3ee7e8994bd1bfd559ab9c61c7 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2342,7 +2342,7 @@ static inline ktime_t sock_read_timestamp(struct sock *sk)
 
 	return kt;
 #else
-	return sk->sk_stamp;
+	return READ_ONCE(sk->sk_stamp);
 #endif
 }
 
@@ -2353,7 +2353,7 @@ static inline void sock_write_timestamp(struct sock *sk, ktime_t kt)
 	sk->sk_stamp = kt;
 	write_sequnlock(&sk->sk_stamp_seq);
 #else
-	sk->sk_stamp = kt;
+	WRITE_ONCE(sk->sk_stamp, kt);
 #endif
 }
 
-- 
2.24.0.rc1.363.gb1bccd3e3d-goog