CLUSTER GETKEYSINSLOT unnecessarily allocates memory

[ghik]

In my tests I wanted to invoke a command which would return all keys from some slot and in order to do this, I passed Int.MaxValue (2³¹-1) as COUNT argument to CLUSTER GETKEYSINSLOT command. The result was Redis crash with an OOM.

It seems that Redis blindly allocates amount of memory proportional to COUNT (https://github.com/antirez/redis/blob/unstable/src/cluster.c#L4267) even though the actual number of keys in the slot may be much smaller.

[antirez]

Hello, yes that's bad... The goal of the command is to return just a few keys per invocation since the command just targets Redis Cluster migrations and everything else should be performed via SCAN, however this is not ok. Btw I'm totally reimplementing this part of Redis as we speak so this will be fixed soon. Thanks.

[antirez]

Thanks, fixed.