[openssl/openssl] 9d67bd: If the loss detection timer has fired we may not h...

[Matt Caswell]

  Branch: refs/heads/openssl-3.2
  Home:   https://github.com/openssl/openssl
  Commit: 9d67bd5ffd9514b791917804f7b839a5b3fb6da2
      https://github.com/openssl/openssl/commit/9d67bd5ffd9514b791917804f7b839a5b3fb6da2
  Author: Matt Caswell <matt at openssl.org>
  Date:   2023-10-30 (Mon, 30 Oct 2023)

  Changed paths:
    M ssl/quic/quic_ackm.c

  Log Message:
  -----------
  If the loss detection timer has fired we may not have lost packets

We calculate the delay from the point that a packet arrives until it will
be counted as lost based on rtt info. Looking at all the packets we can
then calculate the earliest time that a packet will be counted as lost.
When that timer fires the latest rtt info may have changed and therefore
the packet may no longer be counted as lost yet.

We should not assume that just because the ackm timeout has fired that
there will definitely be lost packets.

Fixes #22538

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22541)

(cherry picked from commit 10dfd796c9c25dd78aa88cf84629a0418b8f0866)