From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit 36534d3c54537bf098224a32dc31397793d4594d upstream.
Due to timer wheel implementation, a timer will usually fire
after its schedule.
For instance, for HZ=1000, a timeout between 512ms and 4s
has a granularity of 64ms.
For this range of values, the extra delay could be up to 63ms.
For TCP, this means that tp->rcv_tstamp may be after
inet_csk(sk)->icsk_timeout whenever the timer interrupt
finally triggers, if one packet came during the extra delay.
We need to make sure tcp_rtx_probe0_timed_out() handles this case.
Fixes: e89688e3e978 ("net: tcp: fix unexcepted socket die when snd_wnd is 0")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Menglong Dong <imagedong@xxxxxxxxxxx>
Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Reviewed-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240607125652.1472540-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_timer.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -459,8 +459,13 @@ static bool tcp_rtx_probe0_timed_out(con
{
const struct tcp_sock *tp = tcp_sk(sk);
const int timeout = TCP_RTO_MAX * 2;
- u32 rcv_delta, rtx_delta;
+ u32 rtx_delta;
+ s32 rcv_delta;
+ /* Note: timer interrupt might have been delayed by at least one jiffy,
+ * and tp->rcv_tstamp might very well have been written recently.
+ * rcv_delta can thus be negative.
+ */
rcv_delta = inet_csk(sk)->icsk_timeout - tp->rcv_tstamp;
if (rcv_delta <= timeout)
return false;
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-5.10/tcp_metrics-validate-source-addr-length.patch
queue-5.10/udp-set-sock_rcu_free-earlier-in-udp_lib_get_port.patch
queue-5.10/upstream-tcp-fix-dsack-undo-in-fast-recovery-to-call.patch
queue-5.10/tcp-use-signed-arithmetic-in-tcp_rtx_probe0_timed_out.patch
queue-5.10/tcp-fix-incorrect-undo-caused-by-dsack-of-tlp-retran.patch
queue-5.10/inet_diag-initialize-pad-field-in-struct-inet_diag_r.patch
