syzkaller/pkg/kd/kd.go
Dmitry Vyukov 8136bdad2f pkg/kd: add KD protocol decoder
Very primitive decoder that only decodes amd64 exceptions.
Use it in vm/gce. Now crashes contain something more or less
reasonable which is caught by manager as crash:

BUG: first chance exception 0x80000003

&kd.stateChange64{state:0x3030, processorLevel:0x6, processor:0x0,
numProcessors:0x2, thread:0xffff9c0bd015e080, pc:0xfffff8017615c380,
exception:kd.exception64{code:0x80000003, flags:0x0, record:0x0,
address:0xfffff8017615c380, numParams:0x1, unused:0x0, params:[15]uint64{
0x0, 0x40, 0xfffff801768699e0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0}, firstChance:0x1}, report:kd.controlReport{
dr6:0xffff0ff0, dr7:0x400, eflags:0x86, numInstr:0x10, reportFlags:0x3,
instr:[16]uint8{0xcc, 0xc3, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xf, 0x1f,
0x84, 0x0, 0x0, 0x0, 0x0, 0x0}, cs:0x10, ds:0x2b, es:0x2b, fs:0x53}}
2017-09-28 16:53:58 +02:00

101 lines
2.2 KiB
Go

// Copyright 2017 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.
// Minimal KD protocol decoder.
// KD protocol is used by windows to talk to debuggers. Here are some links:
// https://github.com/radare/radare2/issues/1246#issuecomment-135565901
// http://articles.sysprogs.org/kdvmware/kdcom/
// https://doxygen.reactos.org/df/de3/windbgkd_8h_source.html
package kd
import (
"bytes"
"fmt"
"unsafe"
)
var (
dataHeader = []byte{0x30, 0x30, 0x30, 0x30}
)
const (
typStateChange64 = 7
)
type packet struct {
header uint32
typ uint16
size uint16
id uint32
csum uint32
}
func Decode(data []byte) (start, size int, decoded []byte) {
if len(data) < len(dataHeader) {
return
}
start = bytes.Index(data, dataHeader)
if start == -1 {
start = len(data) - len(dataHeader) - 1
return
}
packetSize := int(unsafe.Sizeof(packet{}))
if len(data)-start < packetSize {
return // incomplete header
}
// Note: assuming little-endian machine.
pkt := (*packet)(unsafe.Pointer(&data[start]))
if len(data)-start < packetSize+int(pkt.size) {
return // incomplete data
}
size = packetSize + int(pkt.size) // skip whole packet
if pkt.typ == typStateChange64 {
if int(pkt.size) < int(unsafe.Sizeof(stateChange64{})) {
return
}
payload := (*stateChange64)(unsafe.Pointer(&data[start+packetSize]))
chance := "second"
if payload.exception.firstChance != 0 {
chance = "first"
}
decoded = []byte(fmt.Sprintf("\n\nBUG: %v chance exception 0x%x\n\n%#v\n\n",
chance, payload.exception.code, payload))
}
return
}
type stateChange64 struct {
state uint32
processorLevel uint16
processor uint16
numProcessors uint32
thread uint64
pc uint64
exception exception64
report controlReport
}
type exception64 struct {
code uint32
flags uint32
record uint64
address uint64
numParams uint32
unused uint32
params [15]uint64
firstChance uint32
}
type controlReport struct {
dr6 uint64
dr7 uint64
eflags uint32
numInstr uint16
reportFlags uint16
instr [16]byte
cs uint16
ds uint16
es uint16
fs uint16
}