From 5fdea3430aed2224a88efa764034ef2ee2b4ccb1 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Thu, 18 Sep 2014 21:43:09 -0400
Subject: runtime: revise TestSetPanicOnFault

We can't assume all those addresses are unmapped.
But at least one should be.

What we're really testing is that the program doesn't crash.

Fixes #8542.

LGTM=iant
R=golang-codereviews, iant, minux
CC=golang-codereviews
https://golang.org/cl/144120043
---
 src/runtime/runtime_test.go | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

(limited to 'src/runtime/runtime_test.go')

diff --git a/src/runtime/runtime_test.go b/src/runtime/runtime_test.go
index cffc9f7d35..3c4075842b 100644
--- a/src/runtime/runtime_test.go
+++ b/src/runtime/runtime_test.go
@@ -157,8 +157,8 @@ var faultAddrs = []uint64{
 	// or else malformed.
 	0xffffffffffffffff,
 	0xfffffffffffff001,
-	// no 0xffffffffffff0001; 0xffff0001 is mapped for 32-bit user space on OS X
-	// no 0xfffffffffff00001; 0xfff00001 is mapped for 32-bit user space sometimes on Linux
+	0xffffffffffff0001,
+	0xfffffffffff00001,
 	0xffffffffff000001,
 	0xfffffffff0000001,
 	0xffffffff00000001,
@@ -182,26 +182,33 @@ func TestSetPanicOnFault(t *testing.T) {
 	old := debug.SetPanicOnFault(true)
 	defer debug.SetPanicOnFault(old)
 
+	nfault := 0
 	for _, addr := range faultAddrs {
-		testSetPanicOnFault(t, uintptr(addr))
+		testSetPanicOnFault(t, uintptr(addr), &nfault)
+	}
+	if nfault == 0 {
+		t.Fatalf("none of the addresses faulted")
 	}
 }
 
-func testSetPanicOnFault(t *testing.T, addr uintptr) {
+func testSetPanicOnFault(t *testing.T, addr uintptr, nfault *int) {
 	if GOOS == "nacl" {
 		t.Skip("nacl doesn't seem to fault on high addresses")
 	}
 
 	defer func() {
-		if err := recover(); err == nil {
-			t.Fatalf("did not find error in recover")
+		if err := recover(); err != nil {
+			*nfault++
 		}
 	}()
 
+	// The read should fault, except that sometimes we hit
+	// addresses that have had C or kernel pages mapped there
+	// readable by user code. So just log the content.
+	// If no addresses fault, we'll fail the test.
 	var p *int
 	p = (*int)(unsafe.Pointer(addr))
-	println(*p)
-	t.Fatalf("still here - should have faulted on address %#x", addr)
+	t.Logf("addr %#x: %#x\n", addr, *p)
 }
 
 func eqstring_generic(s1, s2 string) bool {
-- 
cgit v1.3


From 3b2577ced39194fdd2f1359136c7e176d8de5576 Mon Sep 17 00:00:00 2001
From: Keith Randall <khr@golang.org>
Date: Sat, 20 Sep 2014 23:31:11 -0700
Subject: runtime: be very careful with bad pointer tests

Saw this on a test:

runtime: bad pointer in frame runtime_test.testSetPanicOnFault at 0xc20801c6b0: 0xfff
fatal error: bad pointer!

runtime stack:
...
copystack(0xc2081bf7a0, 0x1000)
        /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/stack.c:621 +0x173 fp=0xfffffd7ffd5ffee0 sp=0xfffffd7ffd5ffe20
runtime.newstack()
        /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/stack.c:774 +0x552 fp=0xfffffd7ffd5fff90 sp=0xfffffd7ffd5ffee0
runtime.morestack()
        /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/asm_amd64.s:324 +0x90 fp=0xfffffd7ffd5fff98 sp=0xfffffd7ffd5fff90

goroutine 163354 [stack growth]:
...
runtime.convT2E(0x587000, 0xc20807bea8, 0x0, 0x0)
        /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/iface.go:141 +0xd2 fp=0xc20801c678 sp=0xc20801c640
runtime_test.testSetPanicOnFault(0xc20822c510, 0xfff, 0xc20801c748)
        /root/work/solaris-amd64-smartos-2dde8b453d26/go/src/runtime/runtime_test.go:211 +0xc6 fp=0xc20801c718 sp=0xc20801c678
...

This test is testing bad pointers.  It loads the bad pointer into a pointer variable,
but before it gets a chance to dereference it, calls convT2E.  That call causes a stack copy,
which exposes that live but bad pointer variable.

LGTM=dvyukov
R=golang-codereviews, dvyukov
CC=golang-codereviews
https://golang.org/cl/146880043
---
 src/runtime/runtime_test.go | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

(limited to 'src/runtime/runtime_test.go')

diff --git a/src/runtime/runtime_test.go b/src/runtime/runtime_test.go
index 3c4075842b..1688364a8e 100644
--- a/src/runtime/runtime_test.go
+++ b/src/runtime/runtime_test.go
@@ -206,9 +206,8 @@ func testSetPanicOnFault(t *testing.T, addr uintptr, nfault *int) {
 	// addresses that have had C or kernel pages mapped there
 	// readable by user code. So just log the content.
 	// If no addresses fault, we'll fail the test.
-	var p *int
-	p = (*int)(unsafe.Pointer(addr))
-	t.Logf("addr %#x: %#x\n", addr, *p)
+	v := *(*byte)(unsafe.Pointer(addr))
+	t.Logf("addr %#x: %#x\n", addr, v)
 }
 
 func eqstring_generic(s1, s2 string) bool {
-- 
cgit v1.3