// SPDX-License-Identifier: GPL-2.0-only
/*
* LZO1X Decompressor from LZO
*
* Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
*
* The full LZO package can be found at:
* http://www.oberhumer.com/opensource/lzo/
*
* Changed for Linux kernel use by:
* Nitin Gupta <nitingupta910@gmail.com>
* Richard Purdie <rpurdie@openedhand.com>
*/
#ifndef STATIC
#include <linux/module.h>
#include <linux/kernel.h>
#endif
#include <linux/unaligned.h>
#include <linux/lzo.h>
#include "lzodefs.h"
#define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x))
#define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x))
#define NEED_IP(x)
if (!HAVE_IP(x))
goto input_overrun
#define NEED_OP(x)
if (!HAVE_OP(x))
goto output_overrun
#define TEST_LB(m_pos)
if ((m_pos) < out)
goto lookbehind_overrun
/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
* count without overflowing an integer. The multiply will overflow when
* multiplying 255 by more than MAXINT/255. The sum will overflow earlier
* depending on the base count. Since the base count is taken from a u8
* and a few bits, it is safe to assume that it will always be lower than
* or equal to 2*255, thus we can always prevent any overflow by accepting
* two less 255 steps. See Documentation/staging/lzo.rst for more information.
*/
#define MAX_255_COUNT ((((size_t)~
0) /
255) -
2)
int lzo1x_decompress_safe(
const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len)
{
unsigned char *op;
const unsigned char *ip;
size_t t, next;
size_t state =
0;
const unsigned char *m_pos;
const unsigned char *
const ip_end = in + in_len;
unsigned char *
const op_end = out + *out_len;
unsigned char bitstream_version;
op = out;
ip = in;
if (unlikely(in_len <
3))
goto input_overrun;
if (likely(in_len >=
5) && likely(*ip ==
17)) {
bitstream_version = ip[
1];
ip +=
2;
}
else {
bitstream_version =
0;
}
if (*ip >
17) {
t = *ip++ -
17;
if (t <
4) {
next = t;
goto match_next;
}
goto copy_literal_run;
}
for (;;) {
t = *ip++;
if (t <
16) {
if (likely(state ==
0)) {
if (unlikely(t ==
0)) {
size_t offset;
const unsigned char *ip_last = ip;
while (unlikely(*ip ==
0)) {
ip++;
NEED_IP(
1);
}
offset = ip - ip_last;
if (unlikely(offset > MAX_255_COUNT))
return LZO_E_ERROR;
offset = (offset <<
8) - offset;
t += offset +
15 + *ip++;
}
t +=
3;
copy_literal_run:
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (likely(HAVE_IP(t +
15) && HAVE_OP(t +
15))) {
const unsigned char *ie = ip + t;
unsigned char *oe = op + t;
do {
COPY8(op, ip);
op +=
8;
ip +=
8;
COPY8(op, ip);
op +=
8;
ip +=
8;
}
while (ip < ie);
ip = ie;
op = oe;
}
else
#endif
{
NEED_OP(t);
NEED_IP(t +
3);
do {
*op++ = *ip++;
}
while (--t >
0);
}
state =
4;
continue;
}
else if (state !=
4) {
next = t &
3;
m_pos = op -
1;
m_pos -= t >>
2;
m_pos -= *ip++ <<
2;
TEST_LB(m_pos);
NEED_OP(
2);
op[
0] = m_pos[
0];
op[
1] = m_pos[
1];
op +=
2;
goto match_next;
}
else {
next = t &
3;
m_pos = op - (
1 + M2_MAX_OFFSET);
m_pos -= t >>
2;
m_pos -= *ip++ <<
2;
t =
3;
}
}
else if (t >=
64) {
next = t &
3;
m_pos = op -
1;
m_pos -= (t >>
2) &
7;
m_pos -= *ip++ <<
3;
t = (t >>
5) -
1 + (
3 -
1);
}
else if (t >=
32) {
t = (t &
31) + (
3 -
1);
if (unlikely(t ==
2)) {
size_t offset;
const unsigned char *ip_last = ip;
while (unlikely(*ip ==
0)) {
ip++;
NEED_IP(
1);
}
offset = ip - ip_last;
if (unlikely(offset > MAX_255_COUNT))
return LZO_E_ERROR;
offset = (offset <<
8) - offset;
t += offset +
31 + *ip++;
NEED_IP(
2);
}
m_pos = op -
1;
next = get_unaligned_le16(ip);
ip +=
2;
m_pos -= next >>
2;
next &=
3;
}
else {
NEED_IP(
2);
next = get_unaligned_le16(ip);
if (((next &
0xfffc) ==
0xfffc) &&
((t &
0xf8) ==
0x18) &&
likely(bitstream_version)) {
NEED_IP(
3);
t &=
7;
t |= ip[
2] <<
3;
t += MIN_ZERO_RUN_LENGTH;
NEED_OP(t);
memset(op,
0, t);
op += t;
next &=
3;
ip +=
3;
goto match_next;
}
else {
m_pos = op;
m_pos -= (t &
8) <<
11;
t = (t &
7) + (
3 -
1);
if (unlikely(t ==
2)) {
size_t offset;
const unsigned char *ip_last = ip;
while (unlikely(*ip ==
0)) {
ip++;
NEED_IP(
1);
}
offset = ip - ip_last;
if (unlikely(offset > MAX_255_COUNT))
return LZO_E_ERROR;
offset = (offset <<
8) - offset;
t += offset +
7 + *ip++;
NEED_IP(
2);
next = get_unaligned_le16(ip);
}
ip +=
2;
m_pos -= next >>
2;
next &=
3;
if (m_pos == op)
goto eof_found;
m_pos -=
0x4000;
}
}
TEST_LB(m_pos);
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (op - m_pos >=
8) {
unsigned char *oe = op + t;
if (likely(HAVE_OP(t +
15))) {
do {
COPY8(op, m_pos);
op +=
8;
m_pos +=
8;
COPY8(op, m_pos);
op +=
8;
m_pos +=
8;
}
while (op < oe);
op = oe;
if (HAVE_IP(
6)) {
state = next;
COPY4(op, ip);
op += next;
ip += next;
continue;
}
}
else {
NEED_OP(t);
do {
*op++ = *m_pos++;
}
while (op < oe);
}
}
else
#endif
{
unsigned char *oe = op + t;
NEED_OP(t);
op[
0] = m_pos[
0];
op[
1] = m_pos[
1];
op +=
2;
m_pos +=
2;
do {
*op++ = *m_pos++;
}
while (op < oe);
}
match_next:
state = next;
t = next;
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (likely(HAVE_IP(
6) && HAVE_OP(
4))) {
COPY4(op, ip);
op += t;
ip += t;
}
else
#endif
{
NEED_IP(t +
3);
NEED_OP(t);
while (t >
0) {
*op++ = *ip++;
t--;
}
}
}
eof_found:
*out_len = op - out;
return (t !=
3 ? LZO_E_ERROR :
ip == ip_end ? LZO_E_OK :
ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
input_overrun:
*out_len = op - out;
return LZO_E_INPUT_OVERRUN;
output_overrun:
*out_len = op - out;
return LZO_E_OUTPUT_OVERRUN;
lookbehind_overrun:
*out_len = op - out;
return LZO_E_LOOKBEHIND_OVERRUN;
}
#ifndef STATIC
EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
MODULE_LICENSE(
"GPL");
MODULE_DESCRIPTION(
"LZO1X Decompressor");
#endif
