diff options
| author | Eric Dumazet <edumazet@google.com> | 2022-01-31 10:26:03 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-02-08 18:23:12 +0100 |
| commit | 0a70f118475e037732557796accd0878a00fc25a (patch) | |
| tree | 267be30de634928f94569584d9802c7a29d0951c | |
| parent | 8070f13e8f938d0160ac6305364c460b8981837a (diff) | |
tcp: fix possible socket leaks in internal pacing mode
This patch is addressing an issue in stable linux-4.19 only.
In linux-4.20, TCP stack adopted EDT (Earliest Departure
Time) model and this issue was incidentally fixed.
Issue at hand was an extra sock_hold() from tcp_internal_pacing()
in paths not using tcp_xmit_retransmit_queue()
Jason Xing reported this leak and provided a patch stopping
the extra sock_hold() to happen.
This patch is more complete and makes sure to avoid
unnecessary extra delays, by reprogramming the high
resolution timer.
Fixes: 73a6bab5aa2a ("tcp: switch pacing timer to softirq based hrtimer")
Reference: https://lore.kernel.org/all/CANn89i+7-wE4xr5D9DpH+N-xkL1SB8oVghCKgz+CT5eG1ODQhA@mail.gmail.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jason Xing <kerneljasonxing@gmail.com>
Reported-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Cc: liweishi <liweishi@kuaishou.com>
Cc: Shujin Li <lishujin@kuaishou.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ipv4/tcp_output.c | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 941c655cad91..c97c027a8d77 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -968,6 +968,8 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) { + struct tcp_sock *tp = tcp_sk(sk); + ktime_t expire, now; u64 len_ns; u32 rate; @@ -979,12 +981,28 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) len_ns = (u64)skb->len * NSEC_PER_SEC; do_div(len_ns, rate); - hrtimer_start(&tcp_sk(sk)->pacing_timer, - ktime_add_ns(ktime_get(), len_ns), + now = ktime_get(); + /* If hrtimer is already armed, then our caller has not + * used tcp_pacing_check(). + */ + if (unlikely(hrtimer_is_queued(&tp->pacing_timer))) { + expire = hrtimer_get_softexpires(&tp->pacing_timer); + if (ktime_after(expire, now)) + now = expire; + if (hrtimer_try_to_cancel(&tp->pacing_timer) == 1) + __sock_put(sk); + } + hrtimer_start(&tp->pacing_timer, ktime_add_ns(now, len_ns), HRTIMER_MODE_ABS_PINNED_SOFT); sock_hold(sk); } +static bool tcp_pacing_check(const struct sock *sk) +{ + return tcp_needs_internal_pacing(sk) && + hrtimer_is_queued(&tcp_sk(sk)->pacing_timer); +} + static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb) { skb->skb_mstamp = tp->tcp_mstamp; @@ -2121,6 +2139,9 @@ static int tcp_mtu_probe(struct sock *sk) if (!tcp_can_coalesce_send_queue_head(sk, probe_size)) return -1; + if (tcp_pacing_check(sk)) + return -1; + /* We're allowed to probe. Build it now. */ nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC, false); if (!nskb) @@ -2194,12 +2215,6 @@ static int tcp_mtu_probe(struct sock *sk) return -1; } -static bool tcp_pacing_check(const struct sock *sk) -{ - return tcp_needs_internal_pacing(sk) && - hrtimer_is_queued(&tcp_sk(sk)->pacing_timer); -} - /* TCP Small Queues : * Control number of packets in qdisc/devices to two packets / or ~1 ms. * (These limits are doubled for retransmits) |