[PATCH 6.4 053/165] net: annotate data-races around sk->sk_max_pacing_rate

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From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit ea7f45ef77b39e72244d282e47f6cb1ef4135cd2 ]

sk_getsockopt() runs locklessly. This means sk->sk_max_pacing_rate
can be read while other threads are changing its value.

Fixes: 62748f32d501 ("net: introduce SO_MAX_PACING_RATE")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/core/sock.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index b25511e7e8103..b87f498072251 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1428,7 +1428,8 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 			cmpxchg(&sk->sk_pacing_status,
 				SK_PACING_NONE,
 				SK_PACING_NEEDED);
-		sk->sk_max_pacing_rate = ulval;
+		/* Pairs with READ_ONCE() from sk_getsockopt() */
+		WRITE_ONCE(sk->sk_max_pacing_rate, ulval);
 		sk->sk_pacing_rate = min(sk->sk_pacing_rate, ulval);
 		break;
 		}
@@ -1855,12 +1856,14 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 #endif
 
 	case SO_MAX_PACING_RATE:
+		/* The READ_ONCE() pair with the WRITE_ONCE() in sk_setsockopt() */
 		if (sizeof(v.ulval) != sizeof(v.val) && len >= sizeof(v.ulval)) {
 			lv = sizeof(v.ulval);
-			v.ulval = sk->sk_max_pacing_rate;
+			v.ulval = READ_ONCE(sk->sk_max_pacing_rate);
 		} else {
 			/* 32bit version */
-			v.val = min_t(unsigned long, sk->sk_max_pacing_rate, ~0U);
+			v.val = min_t(unsigned long, ~0U,
+				      READ_ONCE(sk->sk_max_pacing_rate));
 		}
 		break;
 
-- 
2.40.1






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