BUG: Anonymous maps with adjacent intervals broken since Linux 5.6

[Thorsten Knabe <linux@thorsten-knabe.de>]

Hello.

BUG: Anonymous maps with adjacent intervals are broken starting with
Linux 5.6. Linux 5.5.16 is not affected.

Environment:
- Linux 5.6.3 (AMD64)
- nftables 0.9.4

Trying to apply the ruleset:

flush ruleset

table ip filter {
  chain test {
    ip daddr vmap {
        10.255.1.0-10.255.1.255: accept,
        10.255.2.0-10.255.2.255: drop
    }
  }
}

using nft results in an error on Linux 5.6.3:

# nft -f simple.nft
simple.nft:7:19-5: Error: Could not process rule: File exists
    ip daddr vmap {

The same ruleset works flawlessly using Linux 5.5.16.

Changing the ruleset to:

flush ruleset

table ip filter {
  chain test {
    ip daddr vmap {
        10.255.1.0-10.255.1.254: accept,
        10.255.2.0-10.255.2.255: drop
    }
  }
}

(non adjacent intervals) makes the ruleset work again on Linux 5.6.3.

Reverting commit 7c84d41416d836ef7e533bd4d64ccbdf40c5ac70 from Linux
5.6.3 also fixes the problem.

Kind regards
Thorsten

-- 
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