Backporting CVE-2021-32675 to Redis 4?

[markus-z]

I'm trying to backport the Redis 5 fix for CVE-2021-32675 for Redis 4 for myself

and I'm unclear if I'm doing the right thing and would appreciate advice.

I cherry-picked https://github.com/redis/redis/commit/71be97294 and it applied

cleanly, but the build fails because the third argument for `setProtocolError` is not

set, so I used `pos` for it, which satisfies the build.

My open questions are:

1) Is `pos` the correct value for the 3 argument or should it be `0` or something else

2) Is that enough to patch CVE-2021-32675 for Redis 4?

Thanks in advance,

Markus