GCM and decrypting with Krack
From 2.4 of the paper available at https://www.krackattacks.com (emphasis added):


  The GCMP protocol is based on AES-GCM, meaning it uses
  counter mode for encryption, with the resulting ciphertext being
  authenticated using the GHASH function [28]. Similar to CCMP, it
  is an AEAD cipher, and secure as long as no IV is repeated under a
  particular key. In GCMP, the IV is the concatenation of the sender
  MAC address and a 48-bit nonce. The nonce is also used as a replay
  counter by the receiver, incremented by one before sending each
  frame, and initialized to 0 when installing the TK [1, §12.5.5.4.4].
  This normally assures each IV is only used once. As with CCMP,
  the TK is used directly as the key for both communication directions.
  If a nonce is ever repeated, it is possible to reconstruct the
  authentication key used by the GHASH function [43].


[28] is NIST SP800-37D  (the standard for GCM)
[1] is IEEE 802.11-2016  (the standard for, well, guess)
[43] is 2006 comments by Joux to NIST