fix: invalid frame pointer (#32)

* Update README.md

* fix: invalid frame pointer]

* Update README.md

README.md

@@ -5,7 +5,7 @@
 
 Goref is a Go heap object reference analysis tool based on delve.
 
-It can display the space and object count distribution of Go memory references, which is helpful for efficiently locating memory leak issues or viewing persistent heap objects to optimize GC overhead.
+It can display the space and object count distribution of Go memory references, which is helpful for efficiently locating memory leak issues or viewing persistent heap objects to optimize the garbage collector (GC) overhead.
 
 ## Installation
 
@@ -25,15 +25,15 @@ $ go tool pprof -http=:5079 ./grf.out
 
 The opened HTML page displays the reference distribution of the heap memory. You can choose to view the "inuse space" or "inuse objects".
 
-For example, the following picture is a Heap Profile of pprof. It can be seen that the objects are mainly allocated by `FastRead` function, which is Kitex's deserialization code. This flame graph is not very helpful for troubleshooting because memory allocation for decoding and constructing data is normal.
+For example, the heap profile sampled from a [testing program](https://github.com/cloudwego/goref/blob/main/testdata/mockleak/main.go) is shown below, which reflects the call stack distribution of object creation.
 
-![image](https://github.com/user-attachments/assets/799c1b9a-fcf0-4b35-ab15-03a2bf3a919e)
+![img_v3_02gq_63631612-6f2d-40ce-8f98-a4e52682ef7g](https://github.com/user-attachments/assets/9fb6bded-3f68-4b73-972d-a273c45b7680)
 
-However, by using the goref tool, the following results can be seen: `mockCache` holding onto RPC's Response causing memory not to be released, making the problem clear at a glance.
-
-![image](https://github.com/user-attachments/assets/1c3d5d29-953d-4364-84b9-69ae35f51152)
+By using the goref tool, you can see the memory reference distribution of heap objects reachable by GC, thereby quickly pinpointing the actual code locations holding references.
 
+![img_v3_02gq_53dc2cff-203a-4c06-9678-aae49da4754g](https://github.com/user-attachments/assets/7a6b5a83-e3cd-415f-a5c0-c88d6493e45b)
 
+![img_v3_02gq_54551396-a4ae-42b8-996f-1b1699d381dg](https://github.com/user-attachments/assets/2466c26a-eb78-4be9-af48-7a25e851982a)
 
 It also supports analyzing core files, e.g.
 

pkg/proc/heap.go

@@ -555,7 +555,7 @@ func (s *HeapScope) parseSegment(name string, md *region) *segment {
 // which is extremely complex to handle and is not conducive to the maintenance of the project.
 // Therefore, Goref adopts a conservative scanning scheme.
 // NOTE: This may lead to scanning an additional portion of memory.
-func (s *HeapScope) stackPtrMask(frames []proc.Stackframe) []*framePointerMask {
+func (s *HeapScope) stackPtrMask(start, end Address, frames []proc.Stackframe) []*framePointerMask {
 	var frPtrMasks []*framePointerMask
 	for i := range frames {
 		pc := frames[i].Regs.PC()
@@ -565,6 +565,10 @@ func (s *HeapScope) stackPtrMask(frames []proc.Stackframe) []*framePointerMask {
 		}
 		sp := Address(frames[i].Regs.SP())
 		fp := Address(frames[i].Regs.FrameBase)
+		if fp <= sp || fp > end || sp < start {
+			// invalid frame pointer
+			continue
+		}
 		ptrMask := make([]uint64, CeilDivide(fp.Sub(sp)/8, 64))
 		for i := range ptrMask {
 			ptrMask[i] = ^uint64(0)

pkg/proc/reference.go

@@ -507,7 +507,7 @@ func ObjectReference(t *proc.Target, filename string) error {
 			threadID = gr.Thread.ThreadID()
 		}
 		sf, _ := proc.GoroutineStacktrace(t, gr, 1024, 0)
-		s.g.init(Address(lo), Address(hi), s.stackPtrMask(sf))
+		s.g.init(Address(lo), Address(hi), s.stackPtrMask(Address(lo), Address(hi), sf))
 		if len(sf) > 0 {
 			for i := range sf {
 				ms := myEvalScope{EvalScope: *proc.FrameToScope(t, t.Memory(), gr, threadID, sf[i:]...)}

testdata/mockleak/creator/creator.go

@@ -0,0 +1,54 @@
+package creator
+
+type InnerMessage struct {
+	msgs []string
+}
+
+type MyChan struct {
+	cchan chan *InnerMessage
+}
+
+type SubRequest struct {
+	E map[string]string
+	F map[int64]*MyChan
+}
+
+type Request struct {
+	A *int64
+	B *string
+	C []string
+	D *SubRequest
+	X []*SubRequest
+}
+
+func Create() interface{} {
+	buf := make([]byte, 1024)
+	str := string(buf)
+	return &Request{
+		A: new(int64),
+		B: &str,
+		C: []string{string(buf), string(buf), string(buf)},
+		D: &SubRequest{
+			E: map[string]string{
+				string(buf): string(buf),
+			},
+			F: map[int64]*MyChan{
+				123456: {
+					cchan: make(chan *InnerMessage, 100),
+				},
+			},
+		},
+		X: []*SubRequest{
+			{
+				E: map[string]string{
+					string(buf): string(buf),
+				},
+				F: map[int64]*MyChan{
+					123456: {
+						cchan: make(chan *InnerMessage, 100),
+					},
+				},
+			},
+		},
+	}
+}

testdata/mockleak/holder/holder.go

@@ -0,0 +1,12 @@
+package holder
+
+func ReceiveChan() chan interface{} {
+	ch := make(chan interface{}, 100)
+	go func() {
+		var cached []interface{}
+		for v := range ch {
+			cached = append(cached, v)
+		}
+	}()
+	return ch
+}

testdata/mockleak/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	_ "net/http/pprof"
+	"time"
+
+	"github.com/cloudwego/goref/testdata/mockleak/creator"
+	"github.com/cloudwego/goref/testdata/mockleak/holder"
+)
+
+func main() {
+	go func() {
+		log.Println(http.ListenAndServe("localhost:6060", nil))
+	}()
+	receiver := holder.ReceiveChan()
+	for i := 0; i < 100000; i++ {
+		receiver <- creator.Create()
+	}
+	time.Sleep(1 * time.Minute)
+}