fix(baseapp): correctly check errors before sealing in BaseApp.Init (#24027)

Co-authored-by: Alex | Interchain Labs <alex@interchainlabs.io>

CHANGELOG.md

@@ -53,6 +53,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### Bug Fixes
 
+* (baseapp) [#24027](https://github.com/cosmos/cosmos-sdk/pull/24027) Ensure that `BaseApp.Init` checks that the commit multistore is set to protect against nil dereferences.
 * (x/group) [GHSA-47ww-ff84-4jrg](https://github.com/cosmos/cosmos-sdk/security/advisories/GHSA-47ww-ff84-4jrg) Fix x/group can halt when erroring in EndBlocker
 * (x/distribution) [#23934](https://github.com/cosmos/cosmos-sdk/pull/23934) Fix vulnerability in `incrementReferenceCount` in distribution.
 * (baseapp) [#23879](https://github.com/cosmos/cosmos-sdk/pull/23879) Ensure finalize block response is not empty in the defer check of FinalizeBlock to avoid panic by nil pointer.

baseapp/baseapp.go

@@ -421,16 +421,16 @@ func (app *BaseApp) Init() error {
 		panic("cannot call initFromMainStore: baseapp already sealed")
 	}
 
+	if app.cms == nil {
+		return errors.New("commit multi-store must not be nil")
+	}
+
 	emptyHeader := cmtproto.Header{ChainID: app.chainID}
 
 	// needed for the export command which inits from store but never calls initchain
 	app.setState(execModeCheck, emptyHeader)
 	app.Seal()
 
-	if app.cms == nil {
-		return errors.New("commit multi-store must not be nil")
-	}
-
 	return app.cms.GetPruning().Validate()
 }
 

baseapp/regression_test.go

@@ -0,0 +1,41 @@
+package baseapp
+
+import (
+	"testing"
+
+	dbm "github.com/cosmos/cosmos-db"
+	"github.com/stretchr/testify/require"
+
+	"cosmossdk.io/log"
+	"cosmossdk.io/store"
+	storemetrics "cosmossdk.io/store/metrics"
+)
+
+// Ensures that error checks are performed before sealing the app.
+// Please see https://github.com/cosmos/cosmos-sdk/issues/18726
+func TestNilCmsCheckBeforeSeal(t *testing.T) {
+	app := new(BaseApp)
+
+	// 1. Invoking app.Init with a nil cms MUST not seal the app
+	// and should return an error firstly, which can later be reversed.
+	for i := 0; i < 10; i++ { // N times, the app shouldn't be sealed.
+		err := app.Init()
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "commit multi-store must not be nil")
+		require.False(t, app.IsSealed(), "the app MUST not be sealed")
+	}
+
+	// 2. Now that we've figured out and gotten back an error, let's rectify the problem.
+	// and we should be able to set the commit multistore then reinvoke app.Init successfully!
+	db := dbm.NewMemDB()
+	logger := log.NewTestLogger(t)
+	app.cms = store.NewCommitMultiStore(db, logger, storemetrics.NewNoOpMetrics())
+	err := app.Init()
+	require.Nil(t, err, "app.Init MUST now succeed")
+	require.True(t, app.IsSealed(), "the app must now be sealed")
+
+	// 3. Now we should expect a panic because the app is sealed.
+	require.Panics(t, func() {
+		_ = app.Init()
+	})
+}