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;