[PATCH 6.1 037/127] net: annotate data-races around sk->sk_max_pacing_rate

Greg Kroah-Hartman
2023-08-09T10:54:12Z

From: Eric Dumazet <edumazet@google.com>

[ 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@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 77abd69c56dde..86e88de1238b1 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1426,7 +1426,8 @@ 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;
}
@@ -1852,12 +1853,14 @@ 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