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go/misc/cgo/errors/ptr_test.go
Gernot Vormayr 84fce9832b cmd/cgo: fix check for conversion of ptr to struct field
According to the documentation "When passing a pointer to a field in a
struct, the Go memory in question is the memory occupied by the field,
not the entire struct.". checkAddr states that this should also work
with type conversions, which is implemented in isType. However,
ast.StarExpr must be enclosed in ast.ParenExpr according to the go spec
(see example below), which is not considered in the checks.

Example:
    // struct Si { int i; int *p; }; void f(struct I *x) {}
    import "C"
    type S {
        p *int
        i C.struct_Si
    }
    func main() {
        v := &S{new(int)}
        C.f((*C.struct_I)(&v.i)) // <- panic
    }

This example will cause cgo to emit a cgoCheck that checks the whole
struct S instead of just S.i causing the panic "cgo argument has Go
pointer to Go pointer".

This patch fixes this situation by adding support for ast.ParenExpr to
isType and adds a test, that fails without the fix.

Fixes #32970.

Change-Id: I15ea28c98f839e9fa708859ed107a2e5f1483133
Reviewed-on: https://go-review.googlesource.com/c/go/+/185098
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2019-07-09 19:21:43 +00:00

634 lines
19 KiB
Go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Tests that cgo detects invalid pointer passing at runtime.
package errorstest
import (
"bytes"
"flag"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strings"
"sync/atomic"
"testing"
)
var tmp = flag.String("tmp", "", "use `dir` for temporary files and do not clean up")
// ptrTest is the tests without the boilerplate.
type ptrTest struct {
name string // for reporting
c string // the cgo comment
c1 string // cgo comment forced into non-export cgo file
imports []string // a list of imports
support string // supporting functions
body string // the body of the main function
extra []extra // extra files
fail bool // whether the test should fail
expensive bool // whether the test requires the expensive check
}
type extra struct {
name string
contents string
}
var ptrTests = []ptrTest{
{
// Passing a pointer to a struct that contains a Go pointer.
name: "ptr1",
c: `typedef struct s1 { int *p; } s1; void f1(s1 *ps) {}`,
body: `C.f1(&C.s1{new(C.int)})`,
fail: true,
},
{
// Passing a pointer to a struct that contains a Go pointer.
name: "ptr2",
c: `typedef struct s2 { int *p; } s2; void f2(s2 *ps) {}`,
body: `p := &C.s2{new(C.int)}; C.f2(p)`,
fail: true,
},
{
// Passing a pointer to an int field of a Go struct
// that (irrelevantly) contains a Go pointer.
name: "ok1",
c: `struct s3 { int i; int *p; }; void f3(int *p) {}`,
body: `p := &C.struct_s3{i: 0, p: new(C.int)}; C.f3(&p.i)`,
fail: false,
},
{
// Passing a pointer to a pointer field of a Go struct.
name: "ptrfield",
c: `struct s4 { int i; int *p; }; void f4(int **p) {}`,
body: `p := &C.struct_s4{i: 0, p: new(C.int)}; C.f4(&p.p)`,
fail: true,
},
{
// Passing a pointer to a pointer field of a Go
// struct, where the field does not contain a Go
// pointer, but another field (irrelevantly) does.
name: "ptrfieldok",
c: `struct s5 { int *p1; int *p2; }; void f5(int **p) {}`,
body: `p := &C.struct_s5{p1: nil, p2: new(C.int)}; C.f5(&p.p1)`,
fail: false,
},
{
// Passing the address of a slice with no Go pointers.
name: "sliceok1",
c: `void f6(void **p) {}`,
imports: []string{"unsafe"},
body: `s := []unsafe.Pointer{nil}; C.f6(&s[0])`,
fail: false,
},
{
// Passing the address of a slice with a Go pointer.
name: "sliceptr1",
c: `void f7(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{unsafe.Pointer(&i)}; C.f7(&s[0])`,
fail: true,
},
{
// Passing the address of a slice with a Go pointer,
// where we are passing the address of an element that
// is not a Go pointer.
name: "sliceptr2",
c: `void f8(void **p) {}`,
imports: []string{"unsafe"},
body: `i := 0; s := []unsafe.Pointer{nil, unsafe.Pointer(&i)}; C.f8(&s[0])`,
fail: true,
},
{
// Passing the address of a slice that is an element
// in a struct only looks at the slice.
name: "sliceok2",
c: `void f9(void **p) {}`,
imports: []string{"unsafe"},
support: `type S9 struct { p *int; s []unsafe.Pointer }`,
body: `i := 0; p := &S9{p:&i, s:[]unsafe.Pointer{nil}}; C.f9(&p.s[0])`,
fail: false,
},
{
// Passing the address of a slice of an array that is
// an element in a struct, with a type conversion.
name: "sliceok3",
c: `void f10(void* p) {}`,
imports: []string{"unsafe"},
support: `type S10 struct { p *int; a [4]byte }`,
body: `i := 0; p := &S10{p:&i}; s := p.a[:]; C.f10(unsafe.Pointer(&s[0]))`,
fail: false,
},
{
// Passing the address of a slice of an array that is
// an element in a struct, with a type conversion.
name: "sliceok4",
c: `typedef void* PV11; void f11(PV11 p) {}`,
imports: []string{"unsafe"},
support: `type S11 struct { p *int; a [4]byte }`,
body: `i := 0; p := &S11{p:&i}; C.f11(C.PV11(unsafe.Pointer(&p.a[0])))`,
fail: false,
},
{
// Passing the address of a static variable with no
// pointers doesn't matter.
name: "varok",
c: `void f12(char** parg) {}`,
support: `var hello12 = [...]C.char{'h', 'e', 'l', 'l', 'o'}`,
body: `parg := [1]*C.char{&hello12[0]}; C.f12(&parg[0])`,
fail: false,
},
{
// Passing the address of a static variable with
// pointers does matter.
name: "var1",
c: `void f13(char*** parg) {}`,
support: `var hello13 = [...]*C.char{new(C.char)}`,
body: `parg := [1]**C.char{&hello13[0]}; C.f13(&parg[0])`,
fail: true,
},
{
// Storing a Go pointer into C memory should fail.
name: "barrier",
c: `#include <stdlib.h>
char **f14a() { return malloc(sizeof(char*)); }
void f14b(char **p) {}`,
body: `p := C.f14a(); *p = new(C.char); C.f14b(p)`,
fail: true,
expensive: true,
},
{
// Storing a Go pointer into C memory by assigning a
// large value should fail.
name: "barrierstruct",
c: `#include <stdlib.h>
struct s15 { char *a[10]; };
struct s15 *f15() { return malloc(sizeof(struct s15)); }
void f15b(struct s15 *p) {}`,
body: `p := C.f15(); p.a = [10]*C.char{new(C.char)}; C.f15b(p)`,
fail: true,
expensive: true,
},
{
// Storing a Go pointer into C memory using a slice
// copy should fail.
name: "barrierslice",
c: `#include <stdlib.h>
struct s16 { char *a[10]; };
struct s16 *f16() { return malloc(sizeof(struct s16)); }
void f16b(struct s16 *p) {}`,
body: `p := C.f16(); copy(p.a[:], []*C.char{new(C.char)}); C.f16b(p)`,
fail: true,
expensive: true,
},
{
// A very large value uses a GC program, which is a
// different code path.
name: "barriergcprogarray",
c: `#include <stdlib.h>
struct s17 { char *a[32769]; };
struct s17 *f17() { return malloc(sizeof(struct s17)); }
void f17b(struct s17 *p) {}`,
body: `p := C.f17(); p.a = [32769]*C.char{new(C.char)}; C.f17b(p)`,
fail: true,
expensive: true,
},
{
// Similar case, with a source on the heap.
name: "barriergcprogarrayheap",
c: `#include <stdlib.h>
struct s18 { char *a[32769]; };
struct s18 *f18() { return malloc(sizeof(struct s18)); }
void f18b(struct s18 *p) {}
void f18c(void *p) {}`,
imports: []string{"unsafe"},
body: `p := C.f18(); n := &[32769]*C.char{new(C.char)}; p.a = *n; C.f18b(p); n[0] = nil; C.f18c(unsafe.Pointer(n))`,
fail: true,
expensive: true,
},
{
// A GC program with a struct.
name: "barriergcprogstruct",
c: `#include <stdlib.h>
struct s19a { char *a[32769]; };
struct s19b { struct s19a f; };
struct s19b *f19() { return malloc(sizeof(struct s19b)); }
void f19b(struct s19b *p) {}`,
body: `p := C.f19(); p.f = C.struct_s19a{[32769]*C.char{new(C.char)}}; C.f19b(p)`,
fail: true,
expensive: true,
},
{
// Similar case, with a source on the heap.
name: "barriergcprogstructheap",
c: `#include <stdlib.h>
struct s20a { char *a[32769]; };
struct s20b { struct s20a f; };
struct s20b *f20() { return malloc(sizeof(struct s20b)); }
void f20b(struct s20b *p) {}
void f20c(void *p) {}`,
imports: []string{"unsafe"},
body: `p := C.f20(); n := &C.struct_s20a{[32769]*C.char{new(C.char)}}; p.f = *n; C.f20b(p); n.a[0] = nil; C.f20c(unsafe.Pointer(n))`,
fail: true,
expensive: true,
},
{
// Exported functions may not return Go pointers.
name: "export1",
c: `extern unsigned char *GoFn21();`,
support: `//export GoFn21
func GoFn21() *byte { return new(byte) }`,
body: `C.GoFn21()`,
fail: true,
},
{
// Returning a C pointer is fine.
name: "exportok",
c: `#include <stdlib.h>
extern unsigned char *GoFn22();`,
support: `//export GoFn22
func GoFn22() *byte { return (*byte)(C.malloc(1)) }`,
body: `C.GoFn22()`,
},
{
// Passing a Go string is fine.
name: "passstring",
c: `#include <stddef.h>
typedef struct { const char *p; ptrdiff_t n; } gostring23;
gostring23 f23(gostring23 s) { return s; }`,
imports: []string{"unsafe"},
body: `s := "a"; r := C.f23(*(*C.gostring23)(unsafe.Pointer(&s))); if *(*string)(unsafe.Pointer(&r)) != s { panic(r) }`,
},
{
// Passing a slice of Go strings fails.
name: "passstringslice",
c: `void f24(void *p) {}`,
imports: []string{"strings", "unsafe"},
support: `type S24 struct { a [1]string }`,
body: `s := S24{a:[1]string{strings.Repeat("a", 2)}}; C.f24(unsafe.Pointer(&s.a[0]))`,
fail: true,
},
{
// Exported functions may not return strings.
name: "retstring",
c: `extern void f25();`,
imports: []string{"strings"},
support: `//export GoStr25
func GoStr25() string { return strings.Repeat("a", 2) }`,
body: `C.f25()`,
c1: `#include <stddef.h>
typedef struct { const char *p; ptrdiff_t n; } gostring25;
extern gostring25 GoStr25();
void f25() { GoStr25(); }`,
fail: true,
},
{
// Don't check non-pointer data.
// Uses unsafe code to get a pointer we shouldn't check.
// Although we use unsafe, the uintptr represents an integer
// that happens to have the same representation as a pointer;
// that is, we are testing something that is not unsafe.
name: "ptrdata1",
c: `#include <stdlib.h>
void f26(void* p) {}`,
imports: []string{"unsafe"},
support: `type S26 struct { p *int; a [8*8]byte; u uintptr }`,
body: `i := 0; p := &S26{u:uintptr(unsafe.Pointer(&i))}; q := (*S26)(C.malloc(C.size_t(unsafe.Sizeof(*p)))); *q = *p; C.f26(unsafe.Pointer(q))`,
fail: false,
},
{
// Like ptrdata1, but with a type that uses a GC program.
name: "ptrdata2",
c: `#include <stdlib.h>
void f27(void* p) {}`,
imports: []string{"unsafe"},
support: `type S27 struct { p *int; a [32769*8]byte; q *int; u uintptr }`,
body: `i := 0; p := S27{u:uintptr(unsafe.Pointer(&i))}; q := (*S27)(C.malloc(C.size_t(unsafe.Sizeof(p)))); *q = p; C.f27(unsafe.Pointer(q))`,
fail: false,
},
{
// Check deferred pointers when they are used, not
// when the defer statement is run.
name: "defer1",
c: `typedef struct s28 { int *p; } s28; void f28(s28 *ps) {}`,
body: `p := &C.s28{}; defer C.f28(p); p.p = new(C.int)`,
fail: true,
},
{
// Check a pointer to a union if the union has any
// pointer fields.
name: "union1",
c: `typedef union { char **p; unsigned long i; } u29; void f29(u29 *pu) {}`,
imports: []string{"unsafe"},
body: `var b C.char; p := &b; C.f29((*C.u29)(unsafe.Pointer(&p)))`,
fail: true,
},
{
// Don't check a pointer to a union if the union does
// not have any pointer fields.
// Like ptrdata1 above, the uintptr represents an
// integer that happens to have the same
// representation as a pointer.
name: "union2",
c: `typedef union { unsigned long i; } u39; void f39(u39 *pu) {}`,
imports: []string{"unsafe"},
body: `var b C.char; p := &b; C.f39((*C.u39)(unsafe.Pointer(&p)))`,
fail: false,
},
{
// Test preemption while entering a cgo call. Issue #21306.
name: "preemptduringcall",
c: `void f30() {}`,
imports: []string{"runtime", "sync"},
body: `var wg sync.WaitGroup; wg.Add(100); for i := 0; i < 100; i++ { go func(i int) { for j := 0; j < 100; j++ { C.f30(); runtime.GOMAXPROCS(i) }; wg.Done() }(i) }; wg.Wait()`,
fail: false,
},
{
// Test poller deadline with cgocheck=2. Issue #23435.
name: "deadline",
c: `#define US31 10`,
imports: []string{"os", "time"},
body: `r, _, _ := os.Pipe(); r.SetDeadline(time.Now().Add(C.US31 * time.Microsecond))`,
fail: false,
},
{
// Test for double evaluation of channel receive.
name: "chanrecv",
c: `void f32(char** p) {}`,
imports: []string{"time"},
body: `c := make(chan []*C.char, 2); c <- make([]*C.char, 1); go func() { time.Sleep(10 * time.Second); panic("received twice from chan") }(); C.f32(&(<-c)[0]);`,
fail: false,
},
{
// Test that converting the address of a struct field
// to unsafe.Pointer still just checks that field.
// Issue #25941.
name: "structfield",
c: `void f33(void* p) {}`,
imports: []string{"unsafe"},
support: `type S33 struct { p *int; a [8]byte; u uintptr }`,
body: `s := &S33{p: new(int)}; C.f33(unsafe.Pointer(&s.a))`,
fail: false,
},
{
// Test that converting multiple struct field
// addresses to unsafe.Pointer still just checks those
// fields. Issue #25941.
name: "structfield2",
c: `void f34(void* p, int r, void* s) {}`,
imports: []string{"unsafe"},
support: `type S34 struct { a [8]byte; p *int; b int64; }`,
body: `s := &S34{p: new(int)}; C.f34(unsafe.Pointer(&s.a), 32, unsafe.Pointer(&s.b))`,
fail: false,
},
{
// Test that second argument to cgoCheckPointer is
// evaluated when a deferred function is deferred, not
// when it is run.
name: "defer2",
c: `void f35(char **pc) {}`,
support: `type S35a struct { s []*C.char }; type S35b struct { ps *S35a }`,
body: `p := &S35b{&S35a{[]*C.char{nil}}}; defer C.f35(&p.ps.s[0]); p.ps = nil`,
fail: false,
},
{
// Test that indexing into a function call still
// examines only the slice being indexed.
name: "buffer",
c: `void f36(void *p) {}`,
imports: []string{"bytes", "unsafe"},
body: `var b bytes.Buffer; b.WriteString("a"); C.f36(unsafe.Pointer(&b.Bytes()[0]))`,
fail: false,
},
{
// Test that bgsweep releasing a finalizer is OK.
name: "finalizer",
c: `// Nothing to declare.`,
imports: []string{"os"},
support: `func open37() { os.Open(os.Args[0]) }; var G37 [][]byte`,
body: `for i := 0; i < 10000; i++ { G37 = append(G37, make([]byte, 4096)); if i % 100 == 0 { G37 = nil; open37() } }`,
fail: false,
},
{
// Test that converting generated struct to interface is OK.
name: "structof",
c: `// Nothing to declare.`,
imports: []string{"reflect"},
support: `type MyInt38 int; func (i MyInt38) Get() int { return int(i) }; type Getter38 interface { Get() int }`,
body: `t := reflect.StructOf([]reflect.StructField{{Name: "MyInt38", Type: reflect.TypeOf(MyInt38(0)), Anonymous: true}}); v := reflect.New(t).Elem(); v.Interface().(Getter38).Get()`,
fail: false,
},
{
// Test that a converted address of a struct field results
// in a check for just that field and not the whole struct.
name: "structfieldcast",
c: `struct S40i { int i; int* p; }; void f40(struct S40i* p) {}`,
support: `type S40 struct { p *int; a C.struct_S40i }`,
body: `s := &S40{p: new(int)}; C.f40((*C.struct_S40i)(&s.a))`,
fail: false,
},
}
func TestPointerChecks(t *testing.T) {
dir, exe := buildPtrTests(t)
// We (TestPointerChecks) return before the parallel subtest functions do,
// so we can't just defer os.RemoveAll(dir). Instead we have to wait for
// the parallel subtests to finish. This code looks racy but is not:
// the add +1 run in serial before testOne blocks. The -1 run in parallel
// after testOne finishes.
var pending int32
for _, pt := range ptrTests {
pt := pt
t.Run(pt.name, func(t *testing.T) {
atomic.AddInt32(&pending, +1)
defer func() {
if atomic.AddInt32(&pending, -1) == 0 {
os.RemoveAll(dir)
}
}()
testOne(t, pt, exe)
})
}
}
func buildPtrTests(t *testing.T) (dir, exe string) {
var gopath string
if *tmp != "" {
gopath = *tmp
dir = ""
} else {
d, err := ioutil.TempDir("", filepath.Base(t.Name()))
if err != nil {
t.Fatal(err)
}
dir = d
gopath = d
}
src := filepath.Join(gopath, "src", "ptrtest")
if err := os.MkdirAll(src, 0777); err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(src, "go.mod"), []byte("module ptrtest"), 0666); err != nil {
t.Fatal(err)
}
// Prepare two cgo inputs: one for standard cgo and one for //export cgo.
// (The latter cannot have C definitions, only declarations.)
var cgo1, cgo2 bytes.Buffer
fmt.Fprintf(&cgo1, "package main\n\n/*\n")
fmt.Fprintf(&cgo2, "package main\n\n/*\n")
// C code
for _, pt := range ptrTests {
cgo := &cgo1
if strings.Contains(pt.support, "//export") {
cgo = &cgo2
}
fmt.Fprintf(cgo, "%s\n", pt.c)
fmt.Fprintf(&cgo1, "%s\n", pt.c1)
}
fmt.Fprintf(&cgo1, "*/\nimport \"C\"\n\n")
fmt.Fprintf(&cgo2, "*/\nimport \"C\"\n\n")
// Imports
did1 := make(map[string]bool)
did2 := make(map[string]bool)
did1["os"] = true // for ptrTestMain
fmt.Fprintf(&cgo1, "import \"os\"\n")
for _, pt := range ptrTests {
did := did1
cgo := &cgo1
if strings.Contains(pt.support, "//export") {
did = did2
cgo = &cgo2
}
for _, imp := range pt.imports {
if !did[imp] {
did[imp] = true
fmt.Fprintf(cgo, "import %q\n", imp)
}
}
}
// Func support and bodies.
for _, pt := range ptrTests {
cgo := &cgo1
if strings.Contains(pt.support, "//export") {
cgo = &cgo2
}
fmt.Fprintf(cgo, "%s\nfunc %s() {\n%s\n}\n", pt.support, pt.name, pt.body)
}
// Func list and main dispatch.
fmt.Fprintf(&cgo1, "var funcs = map[string]func() {\n")
for _, pt := range ptrTests {
fmt.Fprintf(&cgo1, "\t%q: %s,\n", pt.name, pt.name)
}
fmt.Fprintf(&cgo1, "}\n\n")
fmt.Fprintf(&cgo1, "%s\n", ptrTestMain)
if err := ioutil.WriteFile(filepath.Join(src, "cgo1.go"), cgo1.Bytes(), 0666); err != nil {
t.Fatal(err)
}
if err := ioutil.WriteFile(filepath.Join(src, "cgo2.go"), cgo2.Bytes(), 0666); err != nil {
t.Fatal(err)
}
cmd := exec.Command("go", "build", "-o", "ptrtest.exe")
cmd.Dir = src
cmd.Env = append(os.Environ(), "GOPATH="+gopath)
out, err := cmd.CombinedOutput()
if err != nil {
t.Fatalf("go build: %v\n%s", err, out)
}
return dir, filepath.Join(src, "ptrtest.exe")
}
const ptrTestMain = `
func main() {
for _, arg := range os.Args[1:] {
f := funcs[arg]
if f == nil {
panic("missing func "+arg)
}
f()
}
}
`
var csem = make(chan bool, 16)
func testOne(t *testing.T, pt ptrTest, exe string) {
t.Parallel()
// Run the tests in parallel, but don't run too many
// executions in parallel, to avoid overloading the system.
runcmd := func(cgocheck string) ([]byte, error) {
csem <- true
defer func() { <-csem }()
cmd := exec.Command(exe, pt.name)
cmd.Env = append(os.Environ(), "GODEBUG=cgocheck="+cgocheck)
return cmd.CombinedOutput()
}
if pt.expensive {
buf, err := runcmd("1")
if err != nil {
t.Logf("%s", buf)
if pt.fail {
t.Fatalf("test marked expensive, but failed when not expensive: %v", err)
} else {
t.Errorf("failed unexpectedly with GODEBUG=cgocheck=1: %v", err)
}
}
}
cgocheck := ""
if pt.expensive {
cgocheck = "2"
}
buf, err := runcmd(cgocheck)
if pt.fail {
if err == nil {
t.Logf("%s", buf)
t.Fatalf("did not fail as expected")
} else if !bytes.Contains(buf, []byte("Go pointer")) {
t.Logf("%s", buf)
t.Fatalf("did not print expected error (failed with %v)", err)
}
} else {
if err != nil {
t.Logf("%s", buf)
t.Fatalf("failed unexpectedly: %v", err)
}
if !pt.expensive {
// Make sure it passes with the expensive checks.
buf, err := runcmd("2")
if err != nil {
t.Logf("%s", buf)
t.Fatalf("failed unexpectedly with expensive checks: %v", err)
}
}
}
if pt.fail {
buf, err := runcmd("0")
if err != nil {
t.Logf("%s", buf)
t.Fatalf("failed unexpectedly with GODEBUG=cgocheck=0: %v", err)
}
}
}