1 // run 2 3 // Copyright 2011 The Go Authors. All rights reserved. 4 // Use of this source code is governed by a BSD-style 5 // license that can be found in the LICENSE file. 6 7 // Test that the implementation catches nil ptr indirection 8 // in a large address space. 9 10 package main 11 12 import "unsafe" 13 14 // Having a big address space means that indexing 15 // at a 256 MB offset from a nil pointer might not 16 // cause a memory access fault. This test checks 17 // that Go is doing the correct explicit checks to catch 18 // these nil pointer accesses, not just relying on the hardware. 19 var dummy [256 << 20]byte // give us a big address space 20 21 func main() { 22 // the test only tests what we intend to test 23 // if dummy starts in the first 256 MB of memory. 24 // otherwise there might not be anything mapped 25 // at the address that might be accidentally 26 // dereferenced below. 27 if uintptr(unsafe.Pointer(&dummy)) > 256<<20 { 28 panic("dummy too far out") 29 } 30 31 shouldPanic(p1) 32 shouldPanic(p2) 33 shouldPanic(p3) 34 shouldPanic(p4) 35 shouldPanic(p5) 36 shouldPanic(p6) 37 shouldPanic(p7) 38 shouldPanic(p8) 39 shouldPanic(p9) 40 shouldPanic(p10) 41 shouldPanic(p11) 42 shouldPanic(p12) 43 shouldPanic(p13) 44 shouldPanic(p14) 45 shouldPanic(p15) 46 shouldPanic(p16) 47 } 48 49 func shouldPanic(f func()) { 50 defer func() { 51 if recover() == nil { 52 panic("memory reference did not panic") 53 } 54 }() 55 f() 56 } 57 58 func p1() { 59 // Array index. 60 var p *[1 << 30]byte = nil 61 println(p[256<<20]) // very likely to be inside dummy, but should panic 62 } 63 64 var xb byte 65 66 func p2() { 67 var p *[1 << 30]byte = nil 68 xb = 123 69 70 // Array index. 71 println(p[uintptr(unsafe.Pointer(&xb))]) // should panic 72 } 73 74 func p3() { 75 // Array to slice. 76 var p *[1 << 30]byte = nil 77 var x []byte = p[0:] // should panic 78 _ = x 79 } 80 81 var q *[1 << 30]byte 82 83 func p4() { 84 // Array to slice. 85 var x []byte 86 var y = &x 87 *y = q[0:] // should crash (uses arraytoslice runtime routine) 88 } 89 90 func fb([]byte) { 91 panic("unreachable") 92 } 93 94 func p5() { 95 // Array to slice. 96 var p *[1 << 30]byte = nil 97 fb(p[0:]) // should crash 98 } 99 100 func p6() { 101 // Array to slice. 102 var p *[1 << 30]byte = nil 103 var _ []byte = p[10 : len(p)-10] // should crash 104 } 105 106 type T struct { 107 x [256 << 20]byte 108 i int 109 } 110 111 func f() *T { 112 return nil 113 } 114 115 var y *T 116 var x = &y 117 118 func p7() { 119 // Struct field access with large offset. 120 println(f().i) // should crash 121 } 122 123 func p8() { 124 // Struct field access with large offset. 125 println((*x).i) // should crash 126 } 127 128 func p9() { 129 // Struct field access with large offset. 130 var t *T 131 println(&t.i) // should crash 132 } 133 134 func p10() { 135 // Struct field access with large offset. 136 var t *T 137 println(t.i) // should crash 138 } 139 140 type T1 struct { 141 T 142 } 143 144 type T2 struct { 145 *T1 146 } 147 148 func p11() { 149 t := &T2{} 150 p := &t.i 151 println(*p) 152 } 153 154 // ADDR(DOT(IND(p))) needs a check also 155 func p12() { 156 var p *T = nil 157 println(*(&((*p).i))) 158 } 159 160 // Tests suggested in golang.org/issue/6080. 161 162 func p13() { 163 var x *[10]int 164 y := x[:] 165 _ = y 166 } 167 168 func p14() { 169 println((*[1]int)(nil)[:]) 170 } 171 172 func p15() { 173 for i := range (*[1]int)(nil)[:] { 174 _ = i 175 } 176 } 177 178 func p16() { 179 for i, v := range (*[1]int)(nil)[:] { 180 _ = i + v 181 } 182 } 183
