From 84afef20f5d960b033c9c8d84710331e6cacec70 Mon Sep 17 00:00:00 2001
From: Emmanuel Odeke <emm.odeke@gmail.com>
Date: Sun, 28 Jan 2018 10:35:34 -0700
Subject: [PATCH 1/2] common: fix BitArray.Update to avoid nil dereference

Update previously only checked that the receiver was
non-nil but didn't check that the input parameter to update
"o" was non-nil causing a nil dereference in cases such as
https://github.com/tendermint/tendermint/blob/fe632ea32a89c3d9804bbd6e3ce9391b1d5a0993/consensus/reactor.go#L306

Fixes https://github.com/tendermint/tendermint/issues/1169
---
 common/bit_array.go      |  2 +-
 common/bit_array_test.go | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/common/bit_array.go b/common/bit_array.go
index 848763b4..68201bad 100644
--- a/common/bit_array.go
+++ b/common/bit_array.go
@@ -306,7 +306,7 @@ func (bA *BitArray) Bytes() []byte {
 // so if necessary, caller must copy or lock o prior to calling Update.
 // If bA is nil, does nothing.
 func (bA *BitArray) Update(o *BitArray) {
-	if bA == nil {
+	if bA == nil || o == nil {
 		return
 	}
 	bA.mtx.Lock()
diff --git a/common/bit_array_test.go b/common/bit_array_test.go
index 1c72882c..9a787e44 100644
--- a/common/bit_array_test.go
+++ b/common/bit_array_test.go
@@ -164,3 +164,26 @@ func TestEmptyFull(t *testing.T) {
 		}
 	}
 }
+
+func TestUpdateNeverPanics(t *testing.T) {
+	newRandBitArray := func(n int) *BitArray {
+		ba, _ := randBitArray(n)
+		return ba
+	}
+	pairs := []struct {
+		a, b *BitArray
+	}{
+		{nil, nil},
+		{newRandBitArray(10), newRandBitArray(12)},
+		{newRandBitArray(0), NewBitArray(10)},
+		{nil, NewBitArray(10)},
+		{nil, newRandBitArray(64)},
+		{newRandBitArray(63), newRandBitArray(64)},
+	}
+
+	for _, pair := range pairs {
+		a, b := pair.a, pair.b
+		a.Update(b)
+		b.Update(a)
+	}
+}

From 85be26c675b05a2a75c856f7c22b446d8df1c944 Mon Sep 17 00:00:00 2001
From: Emmanuel Odeke <emm.odeke@gmail.com>
Date: Sun, 28 Jan 2018 22:02:46 -0700
Subject: [PATCH 2/2] common: BitArray: feedback from @adrianbrink to simplify
 tests

---
 common/bit_array_test.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/common/bit_array_test.go b/common/bit_array_test.go
index 9a787e44..e4ac8bf6 100644
--- a/common/bit_array_test.go
+++ b/common/bit_array_test.go
@@ -175,10 +175,9 @@ func TestUpdateNeverPanics(t *testing.T) {
 	}{
 		{nil, nil},
 		{newRandBitArray(10), newRandBitArray(12)},
-		{newRandBitArray(0), NewBitArray(10)},
+		{newRandBitArray(23), newRandBitArray(23)},
+		{newRandBitArray(37), nil},
 		{nil, NewBitArray(10)},
-		{nil, newRandBitArray(64)},
-		{newRandBitArray(63), newRandBitArray(64)},
 	}
 
 	for _, pair := range pairs {