From 5aaf6afae89a0fc1fbd4dbb7bd76de15223356e4 Mon Sep 17 00:00:00 2001
From: Steven Allen <steven@stebalien.com>
Date: Wed, 27 Jan 2021 12:24:48 -0800
Subject: [PATCH] add additional pre-migration validations

---
 chain/stmgr/forks.go | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/chain/stmgr/forks.go b/chain/stmgr/forks.go
index d7f138c2832..7a8473fc26a 100644
--- a/chain/stmgr/forks.go
+++ b/chain/stmgr/forks.go
@@ -199,10 +199,18 @@ func (us UpgradeSchedule) Validate() error {
 		}
 
 		for _, m := range u.PreMigrations {
+			if m.When < 0 || m.NotAfter < 0 {
+				return xerrors.Errorf("pre-migration must specify non-negative epochs")
+			}
 			if m.When <= m.NotAfter {
 				return xerrors.Errorf("pre-migration cannot end before it starts: %d <= %d", m.When, m.NotAfter)
 			}
 		}
+		if !sort.SliceIsSorted(u.PreMigrations, func(i, j int) bool {
+			return u.PreMigrations[i].When < u.PreMigrations[j].When
+		}) {
+			return xerrors.Errorf("pre-migrations must be sorted by start epoch")
+		}
 	}
 
 	// Make sure the upgrade order makes sense.