Description:
When using / notation to specify a subnet mask, MySQL seems to properly decode /255.0.0.0, /255.255.0.0, /255.255.255.0 and of course /255.255.255.255. It does not seem to properly decode values between such as /255.255.252.0 or /255.255.255.248. As it states in the manual (https://dev.mysql.com/doc/refman/8.4/en/account-names.html), it clearly documents support for classful subnets, but doesn't discuss subnets between the four classful subnets.
How to repeat:
On the server:
mysql> CREATE USER 'foo'@'10.1.2.80/255.255.255.248' IDENTIFIED BY 'bar' ;
mysql> GRANT ALL on baz.* TO 'foo'@'10.1.2.80/255.255.255.248' ;
On a client inside the netmask specified above (not just the exact match, but additional hosts within the mask like 10.1.2.83)
$ mysql -p -u foo -e 'show grants'
Password: bar
MySQL Error 1045: Access denied for user 'foo'@'10.1.2.83' (using password: YES)
Suggested fix:
Verify that all the possible subnet masks and CIDR notations work as expected, not just /8 (255.0.0.0), /16 (255.255.0.0), /24 (255.255.255.0) and /32 (255.255.255.255)
