Randomized fuzzer: slashing period ended before infraction

[ValarDragon]

Steps to Reproduce

In $GOPATH/src/github.com/cosmos/cosmos-sdk/cmd/gaia/app/sim_test.go comment out govsim.SimulateMsgDeposit(app.govKeeper, app.stakeKeeper),.
Then in the makefile, change one of the commands to use -SimulationNumBlocks=500 -SimulationBlockSize=200.

Then you get the following output:

$ make test_sim_gaia_fast
Running quick Gaia simulation. This may take several minutes...
=== RUN   TestFullGaiaSimulation
Starting SimulateFromSeed with randomness created with seed 42
Starting the simulation from time Sun Jan 31 13:59:47 UTC 26140, unixtime 762734152787
Simulating... block 206/500, operation 150/161.--- FAIL: TestFullGaiaSimulation (185.83s)
panic: slashing period ended before infraction: infraction height 207, slashing period ended at 206 [recovered]
	panic: slashing period ended before infraction: infraction height 207, slashing period ended at 206

goroutine 44 [running]:
testing.tRunner.func1(0xc420a07b30)
	/usr/local/go/src/testing/testing.go:742 +0x29d
panic(0xcf5980, 0xc420930df0)
	/usr/local/go/src/runtime/panic.go:502 +0x229
github.com/cosmos/cosmos-sdk/x/slashing.Keeper.capBySlashingPeriod(0x1048320, 0xc420a284b0, 0xc4209f5f80, 0x1055e80, 0xc4209330e0, 0xc4209f5f80, 0x1048320, 0xc420a284e0, 0xa, 0x104f800, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/x/slashing/slashing_period.go:18 +0x32d
github.com/cosmos/cosmos-sdk/x/slashing.Keeper.handleDoubleSign(0x1048320, 0xc420a284b0, 0xc4209f5f80, 0x1055e80, 0xc4209330e0, 0xc4209f5f80, 0x1048320, 0xc420a284e0, 0xa, 0x104f800, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/x/slashing/keeper.go:62 +0x649
github.com/cosmos/cosmos-sdk/x/slashing.BeginBlocker(0x104f800, 0xc4227d6570, 0xc420047600, 0x1a8, 0x0, 0x0, 0x0, 0x0, 0x0, 0xcf, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/x/slashing/tick.go:34 +0x672
github.com/cosmos/cosmos-sdk/cmd/gaia/app.(*GaiaApp).BeginBlocker(0xc4209f0400, 0x104f800, 0xc4227d6570, 0xc420047600, 0x1a8, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/cmd/gaia/app/app.go:143 +0xea
github.com/cosmos/cosmos-sdk/cmd/gaia/app.(*GaiaApp).BeginBlocker-fm(0x104f800, 0xc4227d6570, 0xc420047600, 0x1a8, 0x0, 0x0, 0x0, 0x0, 0x0, 0xcf, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/cmd/gaia/app/app.go:114 +0xba
github.com/cosmos/cosmos-sdk/baseapp.(*BaseApp).BeginBlock(0xc420a205b0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xcf, 0x0, 0xc00edcebe6, 0x15968a0, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/baseapp/baseapp.go:418 +0x23a
github.com/cosmos/cosmos-sdk/x/mock/simulation.SimulateFromSeed(0x10599e0, 0xc420a07b30, 0xc420a205b0, 0xfd0c10, 0x2a, 0xc42064f620, 0xb, 0xb, 0xc420a1df08, 0x0, ...)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/x/mock/simulation/random_simulate_blocks.go:97 +0xbfe
github.com/cosmos/cosmos-sdk/cmd/gaia/app.TestFullGaiaSimulation(0xc420a07b30)
	/home/valar/Code/go/src/github.com/cosmos/cosmos-sdk/cmd/gaia/app/sim_test.go:171 +0x2ac
testing.tRunner(0xc420a07b30, 0xfd0be8)
	/usr/local/go/src/testing/testing.go:777 +0xd0
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:824 +0x2e0
FAIL	github.com/cosmos/cosmos-sdk/cmd/gaia/app	185.862s
Makefile:159: recipe for target 'test_sim_gaia_fast' failed
make: *** [test_sim_gaia_fast] Error 1

This exists on develop.

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned

[ValarDragon]

Its very possible that this could be a bug in the simulator and not the actual state machine.

[cwgoes]

Its very possible that this could be a bug in the simulator and not the actual state machine.

Possibly! I don't immediately know what that would be though - do you mean having incorrect block times or something?

[ValarDragon]

Oh your right, I think we do keep track of the height correctly. It may be that the way we track double sign height in the simulator (or the state machine) is off somewhere though.

[ValarDragon]

/cc @rigelrozanski @alexanderbez @jackzampolin

[cwgoes]

Thanks @rigelrozanski, will tackle ASAP, this should probably block 0.25.

[ValarDragon]

This can now be replicated with:
disable both goverance msgs in sim_test,
run:

go test ./cmd/gaia/app -run TestFullGaiaSimulation -SimulationSeed=741 -SimulationEnabled=true -SimulationNumBlocks=300 -SimulationBlockSize=100 -v -timeout 24h

[cwgoes]

#2430 will close, the height should have been stored as big endian.

[cwgoes]

Closed by #2430.