[thirdparty/linux.git] / lib / lzo / lzo1x_decompress_safe.c

// 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 <asm/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/lzo.txt 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
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
64c70b1c	2	/*
8b975bd3	3	* LZO1X Decompressor from LZO
64c70b1c	4	*
8b975bd3	5	* Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
64c70b1c RP	6	*
	7	* The full LZO package can be found at:
	8	* http://www.oberhumer.com/opensource/lzo/
	9	*
8b975bd3	10	* Changed for Linux kernel use by:
64c70b1c RP	11	* Nitin Gupta <nitingupta910@gmail.com>
	12	* Richard Purdie <rpurdie@openedhand.com>
	13	*/
	14
7dd65feb	15	#ifndef STATIC
64c70b1c RP	16	#include <linux/module.h>
64c70b1c RP	17	#include <linux/kernel.h>
7dd65feb	18	#endif
64c70b1c	19	#include <asm/unaligned.h>
7dd65feb	20	#include <linux/lzo.h>
64c70b1c RP	21	#include "lzodefs.h"
64c70b1c RP	22
af958a38 WT	23	#define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x))
	24	#define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x))
	25	#define NEED_IP(x) if (!HAVE_IP(x)) goto input_overrun
	26	#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
	27	#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
64c70b1c	28
72cf9012 WT	29	/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
	30	* count without overflowing an integer. The multiply will overflow when
	31	* multiplying 255 by more than MAXINT/255. The sum will overflow earlier
	32	* depending on the base count. Since the base count is taken from a u8
	33	* and a few bits, it is safe to assume that it will always be lower than
	34	* or equal to 2*255, thus we can always prevent any overflow by accepting
	35	* two less 255 steps. See Documentation/lzo.txt for more information.
	36	*/
	37	#define MAX_255_COUNT ((((size_t)~0) / 255) - 2)
	38
64c70b1c	39	int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
8b975bd3	40	unsigned char out, size_t out_len)
64c70b1c	41	{
8b975bd3 MO	42	unsigned char *op;
	43	const unsigned char *ip;
	44	size_t t, next;
	45	size_t state = 0;
	46	const unsigned char *m_pos;
64c70b1c RP	47	const unsigned char * const ip_end = in + in_len;
64c70b1c RP	48	unsigned char * const op_end = out + *out_len;
64c70b1c	49
5ee4014a DR	50	unsigned char bitstream_version;
5ee4014a DR	51
8b975bd3 MO	52	op = out;
8b975bd3 MO	53	ip = in;
64c70b1c	54
8b975bd3 MO	55	if (unlikely(in_len < 3))
8b975bd3 MO	56	goto input_overrun;
5ee4014a	57
b11ed18e	58	if (likely(in_len >= 5) && likely(*ip == 17)) {
5ee4014a DR	59	bitstream_version = ip[1];
5ee4014a DR	60	ip += 2;
5ee4014a DR	61	} else {
	62	bitstream_version = 0;
	63	}
	64
64c70b1c RP	65	if (*ip > 17) {
64c70b1c RP	66	t = *ip++ - 17;
8b975bd3 MO	67	if (t < 4) {
8b975bd3 MO	68	next = t;
64c70b1c	69	goto match_next;
64c70b1c	70	}
8b975bd3 MO	71	goto copy_literal_run;
8b975bd3 MO	72	}
64c70b1c	73
8b975bd3	74	for (;;) {
64c70b1c	75	t = *ip++;
8b975bd3 MO	76	if (t < 16) {
	77	if (likely(state == 0)) {
	78	if (unlikely(t == 0)) {
72cf9012 WT	79	size_t offset;
	80	const unsigned char *ip_last = ip;
	81
8b975bd3	82	while (unlikely(*ip == 0)) {
64c70b1c	83	ip++;
af958a38	84	NEED_IP(1);
64c70b1c	85	}
72cf9012 WT	86	offset = ip - ip_last;
	87	if (unlikely(offset > MAX_255_COUNT))
	88	return LZO_E_ERROR;
	89
	90	offset = (offset << 8) - offset;
	91	t += offset + 15 + *ip++;
64c70b1c	92	}
8b975bd3 MO	93	t += 3;
	94	copy_literal_run:
	95	#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
af958a38	96	if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
8b975bd3 MO	97	const unsigned char *ie = ip + t;
	98	unsigned char *oe = op + t;
	99	do {
	100	COPY8(op, ip);
	101	op += 8;
	102	ip += 8;
	103	COPY8(op, ip);
	104	op += 8;
	105	ip += 8;
	106	} while (ip < ie);
	107	ip = ie;
	108	op = oe;
	109	} else
	110	#endif
	111	{
af958a38 WT	112	NEED_OP(t);
af958a38 WT	113	NEED_IP(t + 3);
8b975bd3 MO	114	do {
	115	op++ = ip++;
	116	} while (--t > 0);
64c70b1c	117	}
8b975bd3 MO	118	state = 4;
	119	continue;
	120	} else if (state != 4) {
	121	next = t & 3;
64c70b1c RP	122	m_pos = op - 1;
	123	m_pos -= t >> 2;
	124	m_pos -= *ip++ << 2;
8b975bd3	125	TEST_LB(m_pos);
af958a38	126	NEED_OP(2);
8b975bd3 MO	127	op[0] = m_pos[0];
	128	op[1] = m_pos[1];
	129	op += 2;
	130	goto match_next;
	131	} else {
	132	next = t & 3;
	133	m_pos = op - (1 + M2_MAX_OFFSET);
	134	m_pos -= t >> 2;
	135	m_pos -= *ip++ << 2;
	136	t = 3;
64c70b1c	137	}
8b975bd3 MO	138	} else if (t >= 64) {
	139	next = t & 3;
	140	m_pos = op - 1;
	141	m_pos -= (t >> 2) & 7;
	142	m_pos -= *ip++ << 3;
	143	t = (t >> 5) - 1 + (3 - 1);
	144	} else if (t >= 32) {
	145	t = (t & 31) + (3 - 1);
	146	if (unlikely(t == 2)) {
72cf9012 WT	147	size_t offset;
	148	const unsigned char *ip_last = ip;
	149
8b975bd3	150	while (unlikely(*ip == 0)) {
8b975bd3	151	ip++;
af958a38	152	NEED_IP(1);
8b975bd3	153	}
72cf9012 WT	154	offset = ip - ip_last;
	155	if (unlikely(offset > MAX_255_COUNT))
	156	return LZO_E_ERROR;
	157
	158	offset = (offset << 8) - offset;
	159	t += offset + 31 + *ip++;
af958a38	160	NEED_IP(2);
8b975bd3 MO	161	}
	162	m_pos = op - 1;
	163	next = get_unaligned_le16(ip);
	164	ip += 2;
	165	m_pos -= next >> 2;
	166	next &= 3;
	167	} else {
5ee4014a DR	168	NEED_IP(2);
	169	next = get_unaligned_le16(ip);
	170	if (((next & 0xfffc) == 0xfffc) &&
	171	((t & 0xf8) == 0x18) &&
	172	likely(bitstream_version)) {
	173	NEED_IP(3);
	174	t &= 7;
	175	t \|= ip[2] << 3;
	176	t += MIN_ZERO_RUN_LENGTH;
	177	NEED_OP(t);
	178	memset(op, 0, t);
	179	op += t;
	180	next &= 3;
	181	ip += 3;
	182	goto match_next;
	183	} else {
	184	m_pos = op;
	185	m_pos -= (t & 8) << 11;
	186	t = (t & 7) + (3 - 1);
	187	if (unlikely(t == 2)) {
	188	size_t offset;
	189	const unsigned char *ip_last = ip;
72cf9012	190
5ee4014a DR	191	while (unlikely(*ip == 0)) {
	192	ip++;
	193	NEED_IP(1);
	194	}
	195	offset = ip - ip_last;
	196	if (unlikely(offset > MAX_255_COUNT))
	197	return LZO_E_ERROR;
72cf9012	198
5ee4014a DR	199	offset = (offset << 8) - offset;
	200	t += offset + 7 + *ip++;
	201	NEED_IP(2);
	202	next = get_unaligned_le16(ip);
	203	}
	204	ip += 2;
	205	m_pos -= next >> 2;
	206	next &= 3;
	207	if (m_pos == op)
	208	goto eof_found;
	209	m_pos -= 0x4000;
8b975bd3	210	}
8b975bd3 MO	211	}
	212	TEST_LB(m_pos);
	213	#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
	214	if (op - m_pos >= 8) {
	215	unsigned char *oe = op + t;
af958a38	216	if (likely(HAVE_OP(t + 15))) {
64c70b1c	217	do {
8b975bd3 MO	218	COPY8(op, m_pos);
	219	op += 8;
	220	m_pos += 8;
	221	COPY8(op, m_pos);
	222	op += 8;
	223	m_pos += 8;
	224	} while (op < oe);
	225	op = oe;
af958a38	226	if (HAVE_IP(6)) {
8b975bd3 MO	227	state = next;
	228	COPY4(op, ip);
	229	op += next;
	230	ip += next;
	231	continue;
	232	}
64c70b1c	233	} else {
af958a38	234	NEED_OP(t);
64c70b1c RP	235	do {
64c70b1c RP	236	op++ = m_pos++;
8b975bd3	237	} while (op < oe);
64c70b1c	238	}
8b975bd3 MO	239	} else
	240	#endif
	241	{
	242	unsigned char *oe = op + t;
af958a38	243	NEED_OP(t);
8b975bd3 MO	244	op[0] = m_pos[0];
	245	op[1] = m_pos[1];
	246	op += 2;
	247	m_pos += 2;
	248	do {
	249	op++ = m_pos++;
	250	} while (op < oe);
	251	}
64c70b1c	252	match_next:
8b975bd3 MO	253	state = next;
	254	t = next;
	255	#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
af958a38	256	if (likely(HAVE_IP(6) && HAVE_OP(4))) {
8b975bd3 MO	257	COPY4(op, ip);
	258	op += t;
	259	ip += t;
	260	} else
	261	#endif
	262	{
af958a38 WT	263	NEED_IP(t + 3);
af958a38 WT	264	NEED_OP(t);
8b975bd3	265	while (t > 0) {
64c70b1c	266	op++ = ip++;
8b975bd3	267	t--;
64c70b1c	268	}
8b975bd3	269	}
64c70b1c RP	270	}
64c70b1c RP	271
64c70b1c RP	272	eof_found:
64c70b1c RP	273	*out_len = op - out;
8b975bd3 MO	274	return (t != 3 ? LZO_E_ERROR :
	275	ip == ip_end ? LZO_E_OK :
	276	ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
	277
64c70b1c RP	278	input_overrun:
	279	*out_len = op - out;
	280	return LZO_E_INPUT_OVERRUN;
	281
	282	output_overrun:
	283	*out_len = op - out;
	284	return LZO_E_OUTPUT_OVERRUN;
	285
	286	lookbehind_overrun:
	287	*out_len = op - out;
	288	return LZO_E_LOOKBEHIND_OVERRUN;
	289	}
7dd65feb	290	#ifndef STATIC
64c70b1c RP	291	EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
	292
	293	MODULE_LICENSE("GPL");
	294	MODULE_DESCRIPTION("LZO1X Decompressor");
	295
7dd65feb	296	#endif