proc: do not try to load a non-empty slice if the base address is 0 (#3295)

_fixtures/testvariables2.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"go/constant"
 	"math"
+	"reflect"
 	"runtime"
 	"time"
 	"unsafe"
@@ -371,6 +372,10 @@ func main() {
 	namedA1 := astructName1{12, 45}
 	namedA2 := astructName2{13, 46}
 
+	badslice := []int{1, 2, 3}
+	h := (*reflect.SliceHeader)(unsafe.Pointer(&badslice))
+	h.Data = 0
+
 	var amb1 = 1
 	runtime.Breakpoint()
 	for amb1 := 0; amb1 < 10; amb1++ {
@@ -381,5 +386,5 @@ func main() {
 	longslice := make([]int, 100, 100)
 
 	runtime.Breakpoint()
-	fmt.Println(i1, i2, i3, p1, pp1, amb1, s1, s3, a0, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, m4, m5, upnil, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu, b, b2, sd, anonstruct1, anonstruct2, anoniface1, anonfunc, mapanonstruct1, ifacearr, efacearr, ni8, ni16, ni32, ni64, pinf, ninf, nan, zsvmap, zsslice, zsvar, tm, rettm, errtypednil, emptyslice, emptymap, byteslice, bytestypeslice, runeslice, bytearray, bytetypearray, runearray, longstr, nilstruct, as2, as2.NonPointerRecieverMethod, s4, iface2map, issue1578, ll, unread, w2, w3, w4, w5, longarr, longslice, val, m6, m7, cl, tim1, tim2, typedstringvar, namedA1, namedA2, astructName1(namedA2))
+	fmt.Println(i1, i2, i3, p1, pp1, amb1, s1, s3, a0, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, m4, m5, upnil, up1, i4, i5, i6, err1, err2, errnil, iface1, iface2, ifacenil, arr1, parr, cpx1, const1, iface3, iface4, recursive1, recursive1.x, iface5, iface2fn1, iface2fn2, bencharr, benchparr, mapinf, mainMenu, b, b2, sd, anonstruct1, anonstruct2, anoniface1, anonfunc, mapanonstruct1, ifacearr, efacearr, ni8, ni16, ni32, ni64, pinf, ninf, nan, zsvmap, zsslice, zsvar, tm, rettm, errtypednil, emptyslice, emptymap, byteslice, bytestypeslice, runeslice, bytearray, bytetypearray, runearray, longstr, nilstruct, as2, as2.NonPointerRecieverMethod, s4, iface2map, issue1578, ll, unread, w2, w3, w4, w5, longarr, longslice, val, m6, m7, cl, tim1, tim2, typedstringvar, namedA1, namedA2, astructName1(namedA2), badslice)
 }

pkg/proc/variables.go

@@ -1656,6 +1656,10 @@ func (v *Variable) loadArrayValues(recurseLevel int, cfg LoadConfig) {
 		v.Unreadable = errors.New("Negative array length")
 		return
 	}
+	if v.Base == 0 && v.Len > 0 {
+		v.Unreadable = errors.New("non-zero length array with nil base")
+		return
+	}
 
 	count := v.Len
 	// Cap number of elements

pkg/proc/variables_test.go

@@ -829,6 +829,9 @@ func TestEvalExpression(t *testing.T) {
 
 		// Conversions to ptr-to-ptr types
 		{`**(**runtime.hmap)(uintptr(&m1))`, false, `…`, `…`, "runtime.hmap", nil},
+
+		// Malformed values
+		{`badslice`, false, `(unreadable non-zero length array with nil base)`, `(unreadable non-zero length array with nil base)`, "[]int", nil},
 	}
 
 	ver, _ := goversion.Parse(runtime.Version())