proc: check recursion level when loading pointers (#3431)

Fixes #3429

_fixtures/testvariables2.go

@@ -151,6 +151,8 @@ type ThreeInts struct {
 
 var _ I = (*W2)(nil)
 
+type pptr *pptr
+
 func main() {
 	i1 := 1
 	i2 := 2
@@ -388,6 +390,9 @@ func main() {
 	int3chan <- ThreeInts{a: 2}
 	int3chan <- ThreeInts{a: 3}
 
+	var ptrinf2 pptr
+	ptrinf2 = &ptrinf2
+
 	var amb1 = 1
 	runtime.Breakpoint()
 	for amb1 := 0; amb1 < 10; amb1++ {

pkg/proc/variables.go

@@ -1305,10 +1305,21 @@ func (v *Variable) loadValueInternal(recurseLevel int, cfg LoadConfig) {
 			// Don't increase the recursion level when dereferencing pointers
 			// unless this is a pointer to interface (which could cause an infinite loop)
 			nextLvl := recurseLevel
+			checkLvl := false
 			if v.Children[0].Kind == reflect.Interface {
 				nextLvl++
+			} else if ptyp, isptr := v.RealType.(*godwarf.PtrType); isptr {
+				_, elemTypIsPtr := resolveTypedef(ptyp.Type).(*godwarf.PtrType)
+				if elemTypIsPtr {
+					nextLvl++
+					checkLvl = true
+				}
+			}
+			if checkLvl && recurseLevel > cfg.MaxVariableRecurse {
+				v.Children[0].OnlyAddr = true
+			} else {
+				v.Children[0].loadValueInternal(nextLvl, cfg)
 			}
-			v.Children[0].loadValueInternal(nextLvl, cfg)
 		} else {
 			v.Children[0].OnlyAddr = true
 		}

pkg/proc/variables_test.go

@@ -741,6 +741,8 @@ func getEvalExpressionTestCases() []varTest {
 		{"emptymap", false, `map[string]string []`, `map[string]string []`, "map[string]string", nil},
 		{"mnil", false, `map[string]main.astruct nil`, `map[string]main.astruct nil`, "map[string]main.astruct", nil},
 
+		{"ptrinf2", false, `**(main.pptr)(…`, `(main.pptr)(…`, "main.pptr", nil},
+
 		// conversions between string/[]byte/[]rune (issue #548)
 		{"runeslice", true, `[]int32 len: 4, cap: 4, [116,232,115,116]`, `[]int32 len: 4, cap: 4, [...]`, "[]int32", nil},
 		{"byteslice", true, `[]uint8 len: 5, cap: 5, [116,195,168,115,116]`, `[]uint8 len: 5, cap: 5, [...]`, "[]uint8", nil},