syzkaller/prog/mutation.go
2018-01-27 17:08:43 +01:00

570 lines
13 KiB
Go

// Copyright 2015 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package prog
import (
"fmt"
"math/rand"
"unsafe"
)
const maxBlobLen = uint64(100 << 10)
func (p *Prog) Mutate(rs rand.Source, ncalls int, ct *ChoiceTable, corpus []*Prog) {
r := newRand(p.Target, rs)
retry := false
outer:
for stop := false; !stop || retry; stop = r.oneOf(3) {
retry = false
switch {
case r.nOutOf(1, 100):
// Splice with another prog from corpus.
if len(corpus) == 0 || len(p.Calls) == 0 {
retry = true
continue
}
p0 := corpus[r.Intn(len(corpus))]
p0c := p0.Clone()
idx := r.Intn(len(p.Calls))
p.Calls = append(p.Calls[:idx], append(p0c.Calls, p.Calls[idx:]...)...)
for i := len(p.Calls) - 1; i >= ncalls; i-- {
p.removeCall(i)
}
case r.nOutOf(20, 31):
// Insert a new call.
if len(p.Calls) >= ncalls {
retry = true
continue
}
idx := r.biasedRand(len(p.Calls)+1, 5)
var c *Call
if idx < len(p.Calls) {
c = p.Calls[idx]
}
s := analyze(ct, p, c)
calls := r.generateCall(s, p)
p.insertBefore(c, calls)
case r.nOutOf(10, 11):
// Change args of a call.
if len(p.Calls) == 0 {
retry = true
continue
}
c := p.Calls[r.Intn(len(p.Calls))]
if len(c.Args) == 0 {
retry = true
continue
}
// Mutating mmap() arguments almost certainly doesn't give us new coverage.
if c.Meta == p.Target.MmapSyscall && r.nOutOf(99, 100) {
retry = true
continue
}
s := analyze(ct, p, c)
updateSizes := true
retryArg := false
for stop := false; !stop || retryArg; stop = r.oneOf(3) {
retryArg = false
args, bases, parents := p.Target.mutationArgs(c)
if len(args) == 0 {
retry = true
continue outer
}
idx := r.Intn(len(args))
arg, base, parent := args[idx], bases[idx], parents[idx]
calls, ok := p.Target.mutateArg(r, s, arg, base, parent, &updateSizes)
if !ok {
retryArg = true
continue
}
p.insertBefore(c, calls)
if updateSizes {
p.Target.assignSizesCall(c)
}
p.Target.SanitizeCall(c)
}
default:
// Remove a random call.
if len(p.Calls) == 0 {
retry = true
continue
}
idx := r.Intn(len(p.Calls))
p.removeCall(idx)
}
}
for _, c := range p.Calls {
p.Target.SanitizeCall(c)
}
if debug {
if err := p.validate(); err != nil {
panic(err)
}
}
}
func (target *Target) mutateArg(r *randGen, s *state, arg, base Arg, parent *[]Arg, updateSizes *bool) (calls []*Call, ok bool) {
var baseSize uint64
if base != nil {
b, ok := base.(*PointerArg)
if !ok || b.Res == nil {
panic("bad base arg")
}
baseSize = b.Res.Size()
}
switch t := arg.Type().(type) {
case *IntType, *FlagsType:
a := arg.(*ConstArg)
if r.bin() {
var newArg Arg
newArg, calls = r.generateArg(s, arg.Type())
replaceArg(arg, newArg)
} else {
switch {
case r.nOutOf(1, 3):
a.Val += uint64(r.Intn(4)) + 1
case r.nOutOf(1, 2):
a.Val -= uint64(r.Intn(4)) + 1
default:
a.Val ^= 1 << uint64(r.Intn(64))
}
}
case *LenType:
if !r.mutateSize(arg.(*ConstArg), *parent) {
return nil, false
}
*updateSizes = false
case *ResourceType, *VmaType, *ProcType:
var newArg Arg
newArg, calls = r.generateArg(s, arg.Type())
replaceArg(arg, newArg)
case *BufferType:
a := arg.(*DataArg)
switch t.Kind {
case BufferBlobRand, BufferBlobRange:
data := append([]byte{}, a.Data()...)
minLen, maxLen := uint64(0), maxBlobLen
if t.Kind == BufferBlobRange {
minLen, maxLen = t.RangeBegin, t.RangeEnd
}
a.data = mutateData(r, data, minLen, maxLen)
case BufferString:
data := append([]byte{}, a.Data()...)
if r.bin() {
minLen, maxLen := uint64(0), maxBlobLen
if t.TypeSize != 0 {
minLen, maxLen = t.TypeSize, t.TypeSize
}
a.data = mutateData(r, data, minLen, maxLen)
} else {
a.data = r.randString(s, t)
}
case BufferFilename:
a.data = []byte(r.filename(s))
case BufferText:
data := append([]byte{}, a.Data()...)
a.data = r.mutateText(t.Text, data)
default:
panic("unknown buffer kind")
}
case *ArrayType:
a := arg.(*GroupArg)
count := uint64(0)
switch t.Kind {
case ArrayRandLen:
for count == uint64(len(a.Inner)) {
count = r.randArrayLen()
}
case ArrayRangeLen:
if t.RangeBegin == t.RangeEnd {
panic("trying to mutate fixed length array")
}
for count == uint64(len(a.Inner)) {
count = r.randRange(t.RangeBegin, t.RangeEnd)
}
}
if count > uint64(len(a.Inner)) {
for count > uint64(len(a.Inner)) {
newArg, newCalls := r.generateArg(s, t.Type)
a.Inner = append(a.Inner, newArg)
calls = append(calls, newCalls...)
for _, c := range newCalls {
s.analyze(c)
}
}
} else if count < uint64(len(a.Inner)) {
for _, arg := range a.Inner[count:] {
removeArg(arg)
}
a.Inner = a.Inner[:count]
}
// TODO: swap elements of the array
case *PtrType:
a, ok := arg.(*PointerArg)
if !ok {
break
}
// TODO: we don't know size for out args
size := uint64(1)
if a.Res != nil {
size = a.Res.Size()
}
var newArg Arg
newArg, calls = r.addr(s, t, size, a.Res)
replaceArg(arg, newArg)
case *StructType:
gen := target.SpecialTypes[t.Name()]
if gen == nil {
panic("bad arg returned by mutationArgs: StructType")
}
var newArg Arg
newArg, calls = gen(&Gen{r, s}, t, arg)
for i, f := range newArg.(*GroupArg).Inner {
replaceArg(arg.(*GroupArg).Inner[i], f)
}
case *UnionType:
if gen := target.SpecialTypes[t.Name()]; gen != nil {
var newArg Arg
newArg, calls = gen(&Gen{r, s}, t, arg)
replaceArg(arg, newArg)
} else {
a := arg.(*UnionArg)
current := -1
for i, option := range t.Fields {
if a.Option.Type().FieldName() == option.FieldName() {
current = i
break
}
}
if current == -1 {
panic("can't find current option in union")
}
newIdx := r.Intn(len(t.Fields) - 1)
if newIdx >= current {
newIdx++
}
optType := t.Fields[newIdx]
removeArg(a.Option)
var newOpt Arg
newOpt, calls = r.generateArg(s, optType)
replaceArg(arg, MakeUnionArg(t, newOpt))
}
case *CsumType:
panic("bad arg returned by mutationArgs: CsumType")
case *ConstType:
panic("bad arg returned by mutationArgs: ConstType")
default:
panic(fmt.Sprintf("bad arg returned by mutationArgs: %#v, type=%#v", arg, arg.Type()))
}
// Update base pointer if size has increased.
if base != nil {
b := base.(*PointerArg)
if baseSize < b.Res.Size() {
newArg, newCalls := r.addr(s, b.Type(), b.Res.Size(), b.Res)
calls = append(calls, newCalls...)
a1 := newArg.(*PointerArg)
b.PageIndex = a1.PageIndex
b.PageOffset = a1.PageOffset
b.PagesNum = a1.PagesNum
}
}
for _, c := range calls {
target.SanitizeCall(c)
}
return calls, true
}
func (target *Target) mutationSubargs(arg0 Arg) (args, bases []Arg, parents []*[]Arg) {
ForeachSubarg(arg0, func(arg, base Arg, parent *[]Arg) {
if target.needMutateArg(arg, base, parent) {
args = append(args, arg)
bases = append(bases, base)
parents = append(parents, parent)
}
})
return
}
func (target *Target) mutationArgs(c *Call) (args, bases []Arg, parents []*[]Arg) {
foreachArg(c, func(arg, base Arg, parent *[]Arg) {
if target.needMutateArg(arg, base, parent) {
args = append(args, arg)
bases = append(bases, base)
parents = append(parents, parent)
}
})
return
}
func (target *Target) needMutateArg(arg, base Arg, parent *[]Arg) bool {
switch typ := arg.Type().(type) {
case *StructType:
if target.SpecialTypes[typ.Name()] == nil {
// For structs only individual fields are updated.
return false
}
// These special structs are mutated as a whole.
case *UnionType:
if target.SpecialTypes[typ.Name()] == nil && len(typ.Fields) == 1 {
return false
}
case *ArrayType:
// Don't mutate fixed-size arrays.
if typ.Kind == ArrayRangeLen && typ.RangeBegin == typ.RangeEnd {
return false
}
case *CsumType:
// Checksum is updated when the checksummed data changes.
return false
case *ConstType:
// Well, this is const.
return false
case *BufferType:
if typ.Kind == BufferString && len(typ.Values) == 1 {
return false // string const
}
}
typ := arg.Type()
if typ.Dir() == DirOut || !typ.Varlen() && typ.Size() == 0 {
return false
}
if base != nil {
// TODO(dvyukov): need to check parent as well.
// Say, timespec can be part of another struct and base
// will point to that other struct, not timespec.
// Strictly saying, we need to check parents all way up,
// or better bail out from recursion when we reach
// a special struct.
_, isStruct := base.Type().(*StructType)
_, isUnion := base.Type().(*UnionType)
if (isStruct || isUnion) &&
target.SpecialTypes[base.Type().Name()] != nil {
// These special structs/unions are mutated as a whole.
return false
}
}
return true
}
func mutateData(r *randGen, data []byte, minLen, maxLen uint64) []byte {
const maxInc = 35
retry := false
loop:
for stop := false; !stop || retry; stop = r.oneOf(3) {
retry = false
switch r.Intn(14) {
case 0:
// Append byte.
if uint64(len(data)) >= maxLen {
retry = true
continue loop
}
data = append(data, byte(r.rand(256)))
case 1:
// Remove byte.
if len(data) == 0 || uint64(len(data)) <= minLen {
retry = true
continue loop
}
i := r.Intn(len(data))
copy(data[i:], data[i+1:])
data = data[:len(data)-1]
case 2:
// Replace byte with random value.
if len(data) == 0 {
retry = true
continue loop
}
data[r.Intn(len(data))] = byte(r.rand(256))
case 3:
// Flip bit in byte.
if len(data) == 0 {
retry = true
continue loop
}
byt := r.Intn(len(data))
bit := r.Intn(8)
data[byt] ^= 1 << uint(bit)
case 4:
// Swap two bytes.
if len(data) < 2 {
retry = true
continue loop
}
i1 := r.Intn(len(data))
i2 := r.Intn(len(data))
data[i1], data[i2] = data[i2], data[i1]
case 5:
// Add / subtract from a byte.
if len(data) == 0 {
retry = true
continue loop
}
i := r.Intn(len(data))
delta := byte(r.rand(2*maxInc+1) - maxInc)
if delta == 0 {
delta = 1
}
data[i] += delta
case 6:
// Add / subtract from a uint16.
if len(data) < 2 {
retry = true
continue loop
}
i := r.Intn(len(data) - 1)
p := (*uint16)(unsafe.Pointer(&data[i]))
delta := uint16(r.rand(2*maxInc+1) - maxInc)
if delta == 0 {
delta = 1
}
if r.bin() {
*p += delta
} else {
*p = swap16(swap16(*p) + delta)
}
case 7:
// Add / subtract from a uint32.
if len(data) < 4 {
retry = true
continue loop
}
i := r.Intn(len(data) - 3)
p := (*uint32)(unsafe.Pointer(&data[i]))
delta := uint32(r.rand(2*maxInc+1) - maxInc)
if delta == 0 {
delta = 1
}
if r.bin() {
*p += delta
} else {
*p = swap32(swap32(*p) + delta)
}
case 8:
// Add / subtract from a uint64.
if len(data) < 8 {
retry = true
continue loop
}
i := r.Intn(len(data) - 7)
p := (*uint64)(unsafe.Pointer(&data[i]))
delta := r.rand(2*maxInc+1) - maxInc
if delta == 0 {
delta = 1
}
if r.bin() {
*p += delta
} else {
*p = swap64(swap64(*p) + delta)
}
case 9:
// Set byte to an interesting value.
if len(data) == 0 {
retry = true
continue loop
}
data[r.Intn(len(data))] = byte(r.randInt())
case 10:
// Set uint16 to an interesting value.
if len(data) < 2 {
retry = true
continue loop
}
i := r.Intn(len(data) - 1)
value := uint16(r.randInt())
if r.bin() {
value = swap16(value)
}
*(*uint16)(unsafe.Pointer(&data[i])) = value
case 11:
// Set uint32 to an interesting value.
if len(data) < 4 {
retry = true
continue loop
}
i := r.Intn(len(data) - 3)
value := uint32(r.randInt())
if r.bin() {
value = swap32(value)
}
*(*uint32)(unsafe.Pointer(&data[i])) = value
case 12:
// Set uint64 to an interesting value.
if len(data) < 8 {
retry = true
continue loop
}
i := r.Intn(len(data) - 7)
value := r.randInt()
if r.bin() {
value = swap64(value)
}
*(*uint64)(unsafe.Pointer(&data[i])) = value
case 13:
// Append a bunch of bytes.
if uint64(len(data)) >= maxLen {
retry = true
continue loop
}
const max = 256
n := max - r.biasedRand(max, 10)
if r := int(maxLen) - len(data); n > r {
n = r
}
for i := 0; i < n; i++ {
data = append(data, byte(r.rand(256)))
}
default:
panic("bad")
}
}
return data
}
func swap16(v uint16) uint16 {
v0 := byte(v >> 0)
v1 := byte(v >> 8)
v = 0
v |= uint16(v1) << 0
v |= uint16(v0) << 8
return v
}
func swap32(v uint32) uint32 {
v0 := byte(v >> 0)
v1 := byte(v >> 8)
v2 := byte(v >> 16)
v3 := byte(v >> 24)
v = 0
v |= uint32(v3) << 0
v |= uint32(v2) << 8
v |= uint32(v1) << 16
v |= uint32(v0) << 24
return v
}
func swap64(v uint64) uint64 {
v0 := byte(v >> 0)
v1 := byte(v >> 8)
v2 := byte(v >> 16)
v3 := byte(v >> 24)
v4 := byte(v >> 32)
v5 := byte(v >> 40)
v6 := byte(v >> 48)
v7 := byte(v >> 56)
v = 0
v |= uint64(v7) << 0
v |= uint64(v6) << 8
v |= uint64(v5) << 16
v |= uint64(v4) << 24
v |= uint64(v3) << 32
v |= uint64(v2) << 40
v |= uint64(v1) << 48
v |= uint64(v0) << 56
return v
}