Add Lock Analyzer (#10430)

* add lock analyzer

* fix locks

* progress

* fix failures

* fix error log

Co-authored-by: Raul Jordan <raul@prysmaticlabs.com>

tools/analyzers/recursivelock/analyzer.go

@@ -25,6 +25,45 @@ var Analyzer = &analysis.Analyzer{
 }
 
 var errNestedRLock = errors.New("found recursive read lock call")
+var errNestedLock = errors.New("found recursive lock call")
+var errNestedMixedLock = errors.New("found recursive mixed lock call")
+
+type mode int
+
+const (
+	LockMode = mode(iota)
+	RLockMode
+)
+
+func (m mode) LockName() string {
+	switch m {
+	case LockMode:
+		return "Lock"
+	case RLockMode:
+		return "RLock"
+	}
+	return ""
+}
+
+func (m mode) UnLockName() string {
+	switch m {
+	case LockMode:
+		return "Unlock"
+	case RLockMode:
+		return "RUnlock"
+	}
+	return ""
+}
+
+func (m mode) ErrorFound() error {
+	switch m {
+	case LockMode:
+		return errNestedLock
+	case RLockMode:
+		return errNestedRLock
+	}
+	return nil
+}
 
 func run(pass *analysis.Pass) (interface{}, error) {
 	inspect, ok := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
@@ -33,6 +72,7 @@ func run(pass *analysis.Pass) (interface{}, error) {
 	}
 
 	nodeFilter := []ast.Node{
+		(*ast.GoStmt)(nil),
 		(*ast.CallExpr)(nil),
 		(*ast.DeferStmt)(nil),
 		(*ast.FuncDecl)(nil),
@@ -42,20 +82,36 @@ func run(pass *analysis.Pass) (interface{}, error) {
 		(*ast.ReturnStmt)(nil),
 	}
 
-	keepTrackOf := &tracker{}
+	keepTrackOf := &tracker{
+		rLockTrack: &lockTracker{},
+		lockTrack:  &lockTracker{},
+	}
 	inspect.Preorder(nodeFilter, func(node ast.Node) {
-		if keepTrackOf.funcLitEnd.IsValid() && node.Pos() <= keepTrackOf.funcLitEnd {
+		if keepTrackOf.rLockTrack.funcLitEnd.IsValid() && node.Pos() <= keepTrackOf.rLockTrack.funcLitEnd &&
+			keepTrackOf.lockTrack.funcLitEnd.IsValid() && node.Pos() <= keepTrackOf.lockTrack.funcLitEnd {
 			return
 		}
-		keepTrackOf.funcLitEnd = token.NoPos
-		if keepTrackOf.deferEnd.IsValid() && node.Pos() > keepTrackOf.deferEnd {
-			keepTrackOf.deferEnd = token.NoPos
-		} else if keepTrackOf.deferEnd.IsValid() {
+		keepTrackOf.rLockTrack.funcLitEnd = token.NoPos
+		keepTrackOf.lockTrack.funcLitEnd = token.NoPos
+
+		if keepTrackOf.rLockTrack.deferEnd.IsValid() && node.Pos() > keepTrackOf.rLockTrack.deferEnd {
+			keepTrackOf.rLockTrack.deferEnd = token.NoPos
+		} else if keepTrackOf.rLockTrack.deferEnd.IsValid() {
 			return
 		}
-		if keepTrackOf.retEnd.IsValid() && node.Pos() > keepTrackOf.retEnd {
-			keepTrackOf.retEnd = token.NoPos
-			keepTrackOf.incFRU()
+		if keepTrackOf.lockTrack.deferEnd.IsValid() && node.Pos() > keepTrackOf.lockTrack.deferEnd {
+			keepTrackOf.lockTrack.deferEnd = token.NoPos
+		} else if keepTrackOf.lockTrack.deferEnd.IsValid() {
+			return
+		}
+
+		if keepTrackOf.rLockTrack.retEnd.IsValid() && node.Pos() > keepTrackOf.rLockTrack.retEnd {
+			keepTrackOf.rLockTrack.retEnd = token.NoPos
+			keepTrackOf.rLockTrack.incFRU()
+		}
+		if keepTrackOf.lockTrack.retEnd.IsValid() && node.Pos() > keepTrackOf.lockTrack.retEnd {
+			keepTrackOf.lockTrack.retEnd = token.NoPos
+			keepTrackOf.lockTrack.incFRU()
 		}
 		keepTrackOf = stmtSelector(node, pass, keepTrackOf, inspect)
 	})
@@ -64,57 +120,46 @@ func run(pass *analysis.Pass) (interface{}, error) {
 
 func stmtSelector(node ast.Node, pass *analysis.Pass, keepTrackOf *tracker, inspect *inspector.Inspector) *tracker {
 	switch stmt := node.(type) {
+	case *ast.GoStmt:
+		keepTrackOf.rLockTrack.goroutinePos = stmt.Call.End()
+		keepTrackOf.lockTrack.goroutinePos = stmt.Call.End()
 	case *ast.CallExpr:
+		if stmt.End() == keepTrackOf.rLockTrack.goroutinePos ||
+			stmt.End() == keepTrackOf.lockTrack.goroutinePos {
+			keepTrackOf.rLockTrack.goroutinePos = 0
+			keepTrackOf.lockTrack.goroutinePos = 0
+			break
+		}
 		call := getCallInfo(pass.TypesInfo, stmt)
 		if call == nil {
 			break
 		}
-		name := call.name
 		selMap := mapSelTypes(stmt, pass)
 		if selMap == nil {
 			break
 		}
-		if keepTrackOf.rLockSelector != nil {
-			if keepTrackOf.foundRLock > 0 {
-				if keepTrackOf.rLockSelector.isEqual(selMap, 0) {
-					pass.Reportf(
-						node.Pos(),
-						fmt.Sprintf(
-							"%v",
-							errNestedRLock,
-						),
-					)
-				} else {
-					if stack := hasNestedRLock(keepTrackOf.rLockSelector, selMap, call, inspect, pass, make(map[string]bool)); stack != "" {
-						pass.Reportf(
-							node.Pos(),
-							fmt.Sprintf(
-								"%v\n%v",
-								errNestedRLock,
-								stack,
-							),
-						)
-					}
-				}
-			}
-			if name == "RUnlock" && keepTrackOf.rLockSelector.isEqual(selMap, 1) {
-				keepTrackOf.deincFRU()
-			}
-		} else if name == "RLock" && keepTrackOf.foundRLock == 0 {
-			keepTrackOf.rLockSelector = selMap
-			keepTrackOf.incFRU()
-		}
+		checkForRecLocks(node, pass, inspect, RLockMode, call, keepTrackOf.rLockTrack, selMap)
+		checkForRecLocks(node, pass, inspect, LockMode, call, keepTrackOf.lockTrack, selMap)
 
 	case *ast.File:
-		keepTrackOf = &tracker{}
+		keepTrackOf = &tracker{
+			rLockTrack: &lockTracker{},
+			lockTrack:  &lockTracker{},
+		}
 
 	case *ast.FuncDecl:
-		keepTrackOf = &tracker{}
-		keepTrackOf.funcEnd = stmt.End()
+		keepTrackOf = &tracker{
+			rLockTrack: &lockTracker{},
+			lockTrack:  &lockTracker{},
+		}
+		keepTrackOf.rLockTrack.funcEnd = stmt.End()
 
 	case *ast.FuncLit:
-		if keepTrackOf.funcLitEnd == token.NoPos {
-			keepTrackOf.funcLitEnd = stmt.End()
+		if keepTrackOf.rLockTrack.funcLitEnd == token.NoPos {
+			keepTrackOf.rLockTrack.funcLitEnd = stmt.End()
+		}
+		if keepTrackOf.lockTrack.funcLitEnd == token.NoPos {
+			keepTrackOf.lockTrack.funcLitEnd = stmt.End()
 		}
 	case *ast.IfStmt:
 		stmts := stmt.Body.List
@@ -124,48 +169,113 @@ func stmtSelector(node ast.Node, pass *analysis.Pass, keepTrackOf *tracker, insp
 		keepTrackOf = stmtSelector(stmt.Else, pass, keepTrackOf, inspect)
 	case *ast.DeferStmt:
 		call := getCallInfo(pass.TypesInfo, stmt.Call)
-		if keepTrackOf.deferEnd == token.NoPos {
-			keepTrackOf.deferEnd = stmt.End()
+		if keepTrackOf.rLockTrack.deferEnd == token.NoPos {
+			keepTrackOf.rLockTrack.deferEnd = stmt.End()
 		}
-		if call != nil && call.name == "RUnlock" {
-			keepTrackOf.deferredRUnlock = true
+		if keepTrackOf.lockTrack.deferEnd == token.NoPos {
+			keepTrackOf.lockTrack.deferEnd = stmt.End()
+		}
+
+		if call != nil && call.name == RLockMode.UnLockName() {
+			keepTrackOf.rLockTrack.deferredRUnlock = true
+		}
+		if call != nil && call.name == LockMode.UnLockName() {
+			keepTrackOf.lockTrack.deferredRUnlock = true
 		}
 
 	case *ast.ReturnStmt:
 		for i := 0; i < len(stmt.Results); i++ {
 			keepTrackOf = stmtSelector(stmt.Results[i], pass, keepTrackOf, inspect)
 		}
-		if keepTrackOf.deferredRUnlock && keepTrackOf.retEnd == token.NoPos {
-			keepTrackOf.deincFRU()
-			keepTrackOf.retEnd = stmt.End()
+		if keepTrackOf.rLockTrack.deferredRUnlock && keepTrackOf.rLockTrack.retEnd == token.NoPos {
+			keepTrackOf.rLockTrack.deincFRU()
+			keepTrackOf.rLockTrack.retEnd = stmt.End()
+		}
+		if keepTrackOf.lockTrack.deferredRUnlock && keepTrackOf.lockTrack.retEnd == token.NoPos {
+			keepTrackOf.lockTrack.deincFRU()
+			keepTrackOf.lockTrack.retEnd = stmt.End()
 		}
 	}
 	return keepTrackOf
 }
 
 type tracker struct {
+	rLockTrack *lockTracker
+	lockTrack  *lockTracker
+}
+
+type lockTracker struct {
 	funcEnd         token.Pos
 	retEnd          token.Pos
 	deferEnd        token.Pos
 	funcLitEnd      token.Pos
+	goroutinePos    token.Pos
 	deferredRUnlock bool
 	foundRLock      int
 	rLockSelector   *selIdentList
 }
 
-func (t tracker) String() string {
+func (t lockTracker) String() string {
 	return fmt.Sprintf("funcEnd:%v\nretEnd:%v\ndeferEnd:%v\ndeferredRU:%v\nfoundRLock:%v\n", t.funcEnd, t.retEnd, t.deferEnd, t.deferredRUnlock, t.foundRLock)
 }
 
-func (t *tracker) deincFRU() {
+func (t *lockTracker) deincFRU() {
 	if t.foundRLock > 0 {
 		t.foundRLock -= 1
 	}
 }
-func (t *tracker) incFRU() {
+func (t *lockTracker) incFRU() {
 	t.foundRLock += 1
 }
 
+func checkForRecLocks(node ast.Node, pass *analysis.Pass, inspect *inspector.Inspector, lockmode mode, call *callInfo,
+	lockTracker *lockTracker, selMap *selIdentList) {
+	name := call.name
+	if lockTracker.rLockSelector != nil {
+		if lockTracker.foundRLock > 0 {
+			if lockTracker.rLockSelector.isRelated(selMap, 0) {
+				pass.Reportf(
+					node.Pos(),
+					fmt.Sprintf(
+						"%v",
+						errNestedMixedLock,
+					),
+				)
+			}
+			if lockTracker.rLockSelector.isEqual(selMap, 0) {
+				pass.Reportf(
+					node.Pos(),
+					fmt.Sprintf(
+						"%v",
+						lockmode.ErrorFound(),
+					),
+				)
+			} else {
+				if stack := hasNestedlock(lockTracker.rLockSelector, lockTracker.goroutinePos, selMap, call, inspect, pass, make(map[string]bool),
+					lockmode.UnLockName()); stack != "" {
+					pass.Reportf(
+						node.Pos(),
+						fmt.Sprintf(
+							"%v\n%v",
+							lockmode.ErrorFound(),
+							stack,
+						),
+					)
+				}
+			}
+		}
+		if name == lockmode.UnLockName() && lockTracker.rLockSelector.isEqual(selMap, 1) {
+			lockTracker.deincFRU()
+		}
+		if name == lockmode.LockName() && lockTracker.foundRLock == 0 && lockTracker.rLockSelector.isEqual(selMap, 0) {
+			lockTracker.incFRU()
+		}
+	} else if name == lockmode.LockName() && lockTracker.foundRLock == 0 {
+		lockTracker.rLockSelector = selMap
+		lockTracker.incFRU()
+	}
+}
+
 // Stores the AST and type information of a single item in a selector expression
 // For example, "a.b.c()", a selIdentNode might store the information for "a"
 type selIdentNode struct {
@@ -221,6 +331,45 @@ func (s *selIdentList) isEqual(s2 *selIdentList, offset int) bool {
 	return true
 }
 
+// isRelated checks if our selectors are of the same type and
+// reference the same underlying object. If they do we check
+// if the provided list is referencing a non-equal but related
+// lock. Ex: Lock - RLock, RLock - Lock
+// TODO: Use a generalizable method here instead of hardcoding
+// the lock definitions here.
+func (s *selIdentList) isRelated(s2 *selIdentList, offset int) bool {
+	if s2 == nil || (s.length != s2.length) {
+		return false
+	}
+	s.reset()
+	s2.reset()
+	for i := true; i; {
+		if !s.current.isEqual(s2.current) {
+			return false
+		}
+		if s.currentIndex < s.length-offset-1 && s.next() != nil {
+			s2.next()
+		} else {
+			i = false
+		}
+		// Only check if we are at the last index for
+		// related method calls.
+		if s.currentIndex == s.length-1 {
+			switch s.current.this.String() {
+			case LockMode.LockName():
+				if s2.current.this.String() == RLockMode.LockName() {
+					return true
+				}
+			case RLockMode.LockName():
+				if s2.current.this.String() == LockMode.LockName() {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
 // getSub returns the shared beginning selIdentList of s and s2,
 // if s contains all elements (except the last) of s2,
 // and returns nil otherwise.
@@ -356,11 +505,12 @@ func interfaceMethod(s *types.Signature) bool {
 	return recv != nil && types.IsInterface(recv.Type())
 }
 
-// hasNestedRLock returns a stack trace of the nested or recursive RLock within the declaration of a function/method call (given by call).
-// If the call expression does not contain a nested or recursive RLock, hasNestedRLock returns an empty string.
-// hasNestedRLock finds a nested or recursive RLock by recursively calling itself on any functions called by the function/method represented
+// hasNestedlock returns a stack trace of the nested or recursive lock within the declaration of a function/method call (given by call).
+// If the call expression does not contain a nested or recursive lock, hasNestedlock returns an empty string.
+// hasNestedlock finds a nested or recursive lock by recursively calling itself on any functions called by the function/method represented
 // by callInfo.
-func hasNestedRLock(fullRLockSelector *selIdentList, compareMap *selIdentList, call *callInfo, inspect *inspector.Inspector, pass *analysis.Pass, hist map[string]bool) (retStack string) {
+func hasNestedlock(fullRLockSelector *selIdentList, goPos token.Pos, compareMap *selIdentList, call *callInfo, inspect *inspector.Inspector,
+	pass *analysis.Pass, hist map[string]bool, lockName string) (retStack string) {
 	var rLockSelector *selIdentList
 	f := pass.Fset
 	tInfo := pass.TypesInfo
@@ -390,20 +540,26 @@ func hasNestedRLock(fullRLockSelector *selIdentList, compareMap *selIdentList, c
 	addition := fmt.Sprintf("\t%q at %v\n", call.name, f.Position(call.call.Pos()))
 	ast.Inspect(node, func(iNode ast.Node) bool {
 		switch stmt := iNode.(type) {
+		case *ast.GoStmt:
+			goPos = stmt.End()
 		case *ast.CallExpr:
+			if stmt.End() == goPos {
+				goPos = 0
+				return false
+			}
 			c := getCallInfo(tInfo, stmt)
 			if c == nil {
 				return false
 			}
 			name := c.name
 			selMap := mapSelTypes(stmt, pass)
-			if rLockSelector.isEqual(selMap, 0) { // if the method found is an RLock method
+			if rLockSelector.isEqual(selMap, 0) || rLockSelector.isRelated(selMap, 0) { // if the method found is an RLock method
 				retStack += addition + fmt.Sprintf("\t%q at %v\n", name, f.Position(iNode.Pos()))
-			} else if name != "RUnlock" { // name should not equal the previousName to prevent infinite recursive loop
+			} else if name != lockName { // name should not equal the previousName to prevent infinite recursive loop
 				nt := c.id
 				if !hist[nt] { // make sure we are not in an infinite recursive loop
 					hist[nt] = true
-					stack := hasNestedRLock(rLockSelector, selMap, c, inspect, pass, hist)
+					stack := hasNestedlock(rLockSelector, goPos, selMap, c, inspect, pass, hist, lockName)
 					delete(hist, nt)
 					if stack != "" {
 						retStack += addition + stack

tools/analyzers/recursivelock/testdata/badlockswithmethods.go

@@ -13,6 +13,31 @@ func (p *ProtectResource) NestedMethod2() {
 	p.RUnlock()
 }
 
+func (p *ProtectResource) NestedMethodMixedLock() {
+	p.Lock()
+	p.GetResource() // want `found recursive lock call`
+	p.Unlock()
+}
+
+func (p *ProtectResource) MixedLock() {
+	p.RLock()
+	p.Lock() // want `found recursive mixed lock call`
+	p.Unlock()
+	p.RUnlock()
+}
+
+func (p *ProtectResource) NestedMethodGoroutine() {
+	p.RLock()
+	defer p.RUnlock()
+	go p.GetResource()
+}
+
+func (p *ProtectResource) NestedResourceGoroutine() {
+	p.RLock()
+	defer p.RUnlock()
+	p.GetResourceNestedGoroutine()
+}
+
 func (p *NestedProtectResource) MultiLevelStruct() {
 	p.nestedPR.RLock()
 	p.nestedPR.GetResource() // want `found recursive read lock call`

tools/analyzers/recursivelock/testdata/complexlocks.go

@@ -15,9 +15,30 @@ func (p *ProtectResource) FuncLitInStructLit() {
 	p.RUnlock()
 }
 
+func (p *ProtectResource) FuncLitInStructLitLocked() {
+	p.Lock()
+	type funcLitContainer struct {
+		funcLit func()
+	}
+	var fl *funcLitContainer = &funcLitContainer{
+		funcLit: func() {
+			p.Lock()
+		},
+	}
+	fl.funcLit() // this is a nested Lock but won't be caught
+	p.Unlock()
+}
+
 func (e *ExposedMutex) FuncReturnsMutex() {
 	e.GetLock().RLock()
 	e.lock.RLock() // this is an obvious nested lock, but won't be caught since the first RLock was called through a getter function
 	e.lock.RUnlock()
 	e.GetLock().RUnlock()
 }
+
+func (e *ExposedMutex) FuncReturnsMutexLocked() {
+	e.GetLock().Lock()
+	e.lock.Lock() // this is an obvious nested lock, but won't be caught since the first RLock was called through a getter function
+	e.lock.Unlock()
+	e.GetLock().Unlock()
+}

tools/analyzers/recursivelock/testdata/nonrlocks.go

@@ -12,3 +12,15 @@ func (resource *NestedProtectResource) NonNestedRLockDifferentRLocks() {
 	resource.GetNestedPResource() // get nested resource uses RLock, but at a deeper level in the struct
 	resource.RUnlock()
 }
+
+func (resource *ProtectResource) NestedLockWithDefer() string {
+	resource.Lock()
+	defer resource.Unlock()
+	return resource.GetResourceLocked() // want `found recursive lock call`
+}
+
+func (resource *NestedProtectResource) NonNestedLockDifferentLocks() {
+	resource.Lock()
+	resource.GetNestedPResourceLocked() // get nested resource uses RLock, but at a deeper level in the struct
+	resource.Unlock()
+}

tools/analyzers/recursivelock/testdata/types.go

@@ -15,10 +15,24 @@ func (r *ProtectResource) GetResource() string {
 	return r.resource
 }
 
+func (r *ProtectResource) GetResourceLocked() string {
+	defer r.Unlock()
+	r.Lock()
+	return r.resource
+}
+
 func (r *ProtectResource) GetResourceNested() string {
 	return r.GetResource()
 }
 
+func (r *ProtectResource) GetResourceNestedGoroutine() {
+	go r.GetResource()
+}
+
+func (r *ProtectResource) GetResourceNestedLock() string {
+	return r.GetResourceLocked()
+}
+
 type NestedProtectResource struct {
 	*sync.RWMutex
 	nestedPR ProtectResource
@@ -30,6 +44,12 @@ func (r *NestedProtectResource) GetNestedPResource() string {
 	return r.nestedPR.resource
 }
 
+func (r *NestedProtectResource) GetNestedPResourceLocked() string {
+	defer r.nestedPR.Unlock()
+	r.nestedPR.Lock()
+	return r.nestedPR.resource
+}
+
 type NotProtected struct {
 	resource string
 }