From 1ff69133d44003d65cd1e1ee8e79331471f8d142 Mon Sep 17 00:00:00 2001
From: "mergify[bot]" <37929162+mergify[bot]@users.noreply.github.com>
Date: Tue, 1 Mar 2022 13:03:19 +0100
Subject: [PATCH] fix: classify client states without consensus states as
 expired (backport #941) (#1011)

* fix: classify client states without consensus states as expired (#941)

## Description

closes: #850

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/ibc-go/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
- [ ] Re-reviewed `Files changed` in the Github PR explorer
- [ ] Review `Codecov Report` in the comment section below once CI passes

(cherry picked from commit d48f576a0b2fe752790339f9e6f99b99d9fe2486)

* add changelog entry

Co-authored-by: Tim Lind <tim@incremental.co>
Co-authored-by: Carlos Rodriguez <crodveg@gmail.com>
Co-authored-by: Carlos Rodriguez <carlos@interchain.io>
---
 CHANGELOG.md                                                  | 1 +
 modules/core/02-client/keeper/grpc_query_test.go              | 2 +-
 modules/light-clients/07-tendermint/types/client_state.go     | 4 +++-
 .../light-clients/07-tendermint/types/client_state_test.go    | 4 ++--
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a6d2cc0b5ef..29c887cb19a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -47,6 +47,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (client) [\#941](https://github.com/cosmos/ibc-go/pull/941) Classify client states without consensus states as expired
 * (transfer) [\#978](https://github.com/cosmos/ibc-go/pull/978) Support base denoms with slashes in denom validation
 
 ## [v2.0.3](https://github.com/cosmos/ibc-go/releases/tag/v2.0.2) - 2022-02-03
diff --git a/modules/core/02-client/keeper/grpc_query_test.go b/modules/core/02-client/keeper/grpc_query_test.go
index 6dc9cbfc5bc..33b97cc1db1 100644
--- a/modules/core/02-client/keeper/grpc_query_test.go
+++ b/modules/core/02-client/keeper/grpc_query_test.go
@@ -452,7 +452,7 @@ func (suite *KeeperTestSuite) TestQueryClientStatus() {
 					ClientId: path.EndpointA.ClientID,
 				}
 			},
-			true, exported.Unknown.String(),
+			true, exported.Expired.String(),
 		},
 		{
 			"Frozen client status",
diff --git a/modules/light-clients/07-tendermint/types/client_state.go b/modules/light-clients/07-tendermint/types/client_state.go
index 2448d2859bb..72b688e6a84 100644
--- a/modules/light-clients/07-tendermint/types/client_state.go
+++ b/modules/light-clients/07-tendermint/types/client_state.go
@@ -78,7 +78,9 @@ func (cs ClientState) Status(
 	// get latest consensus state from clientStore to check for expiry
 	consState, err := GetConsensusState(clientStore, cdc, cs.GetLatestHeight())
 	if err != nil {
-		return exported.Unknown
+		// if the client state does not have an associated consensus state for its latest height
+		// then it must be expired
+		return exported.Expired
 	}
 
 	if cs.IsExpired(consState.Timestamp, ctx.BlockTime()) {
diff --git a/modules/light-clients/07-tendermint/types/client_state_test.go b/modules/light-clients/07-tendermint/types/client_state_test.go
index 7a3f185370b..4e05f038de3 100644
--- a/modules/light-clients/07-tendermint/types/client_state_test.go
+++ b/modules/light-clients/07-tendermint/types/client_state_test.go
@@ -47,10 +47,10 @@ func (suite *TendermintTestSuite) TestStatus() {
 			clientState.FrozenHeight = clienttypes.NewHeight(0, 1)
 			path.EndpointA.SetClientState(clientState)
 		}, exported.Frozen},
-		{"client status is unknown", func() {
+		{"client status without consensus state", func() {
 			clientState.LatestHeight = clientState.LatestHeight.Increment().(clienttypes.Height)
 			path.EndpointA.SetClientState(clientState)
-		}, exported.Unknown},
+		}, exported.Expired},
 		{"client status is expired", func() {
 			suite.coordinator.IncrementTimeBy(clientState.TrustingPeriod)
 		}, exported.Expired},