netdev - kTLS broken somewhere between 4.18 and 5.0

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Message-ID: <20190413153435.73ecztpnbivrckvj@sesse.net>
Date:   Sat, 13 Apr 2019 17:34:35 +0200
From:   "Steinar H. Gunderson" <steinar+kernel@...derson.no>
To:     netdev@...r.kernel.org
Subject: kTLS broken somewhere between 4.18 and 5.0

Hi,

I've been using kTLS for a while, with my video reflector Cubemap
(https://git.sesse.net/?p=cubemap). After I upgraded my server from
4.18.11 to 5.0.6, seemingly I've started seeing corruption. The data sent
with send() (HTTP headers, HLS playlists) appears to be fine, but sendfile()
(actual video data, from a file on tmpfs) is not; after ~20 kB of data
(19626 in one test here), the data appears to be randomly corrupted. Diffing
non-TLS (good) and TLS (bad) video data:

  00004c70: fa 70 c5 71 b5 f5 b7 ac 74 b0 ca 80 02 4c 06 3f  .p.q....t....L.?
  00004c80: 5c 5b 0c b3 e0 a0 c3 21 93 d3 6e 65 36 70 0a 27  \[.....!..ne6p.'
  00004c90: 84 67 16 2c 95 c0 55 e1 04 76 52 10 50 5d 00 26  .g.,..U..vR.P].&

 -00004ca0: 0c b8 84 70 7e ed 12 8f 5e 7e 18 c0 06 20 02 54  ...p~...^~... .T
 +00004ca0: 0c b8 84 70 7e ed 12 8f 5e 7e 0a 60 9f 1f 97 f2  ...p~...^~.`....

 -00004cb0: 1e 4c c1 71 7d 0b 91 28 23 98 09 ae c4 95 ae 7f  .L.q}..(#.......
 +00004cb0: 6e 17 50 03 67 fa 2f 83 b0 88 eb fc 54 f2 0b 00  n.P.g./.....T...

 -00004cc0: a2 92 20 b8 f2 b6 72 2a e8 7e d7 27 99 65 56 70  .. ...r*.~.'.eVp
 +00004cc0: 6c 9e a1 02 b4 30 11 25 d7 58 b0 0c c0 6c e1 bd  l....0.%.X...l..

It never appears to get back into sync after that. Interestingly, it is
_consistently_ wrong; if I download the same fragment multiple times, it
breaks at the same place and gives the same garbage (but different fragments
give different divergence points). Tested with both wget and Chrome.
Does anyone know what could be wrong?

(It is, unfortunately, not easy for me to reboot this server at will, so a
bisect could be hard.)

Please Cc me on any replies, I'm not subscribed to netdev.

/* Steinar */
-- 
Homepage: https://www.sesse.net/