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linux_dsm_epyc7002/lib/lzo/lzo1x_compress.c
Dave Rodgman b5265c813c lib/lzo: fix ambiguous encoding bug in lzo-rle 
In some rare cases, for input data over 32 KB, lzo-rle could encode two
different inputs to the same compressed representation, so that
decompression is then ambiguous (i.e.  data may be corrupted - although
zram is not affected because it operates over 4 KB pages).

This modifies the compressor without changing the decompressor or the
bitstream format, such that:

 - there is no change to how data produced by the old compressor is
   decompressed

 - an old decompressor will correctly decode data from the updated
   compressor

 - performance and compression ratio are not affected

 - we avoid introducing a new bitstream format

In testing over 12.8M real-world files totalling 903 GB, three files
were affected by this bug.  I also constructed 37M semi-random 64 KB
files totalling 2.27 TB, and saw no affected files.  Finally I tested
over files constructed to contain each of the ~1024 possible bad input
sequences; for all of these cases, updated lzo-rle worked correctly.

There is no significant impact to performance or compression ratio.

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Rodgman <dave.rodgman@arm.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Markus F.X.J. Oberhumer <markus@oberhumer.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Chao Yu <yuchao0@huawei.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200507100203.29785-1-dave.rodgman@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-11 18:17:47 -07:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* LZO1X Compressor 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>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <asm/unaligned.h>
#include <linux/lzo.h>
#include "lzodefs.h"
static noinline size_t
lzo1x_1_do_compress(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len,
size_t ti, void *wrkmem, signed char *state_offset,
const unsigned char bitstream_version)
{
const unsigned char *ip;
unsigned char *op;
const unsigned char * const in_end = in + in_len;
const unsigned char * const ip_end = in + in_len - 20;
const unsigned char *ii;
lzo_dict_t * const dict = (lzo_dict_t *) wrkmem;
op = out;
ip = in;
ii = ip;
ip += ti < 4 ? 4 - ti : 0;
for (;;) {
const unsigned char *m_pos = NULL;
size_t t, m_len, m_off;
u32 dv;
u32 run_length = 0;
literal:
ip += 1 + ((ip - ii) >> 5);
next:
if (unlikely(ip >= ip_end))
break;
dv = get_unaligned_le32(ip);
if (dv == 0 && bitstream_version) {
const unsigned char *ir = ip + 4;
const unsigned char *limit = ip_end
< (ip + MAX_ZERO_RUN_LENGTH + 1)
? ip_end : ip + MAX_ZERO_RUN_LENGTH + 1;
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && \
defined(LZO_FAST_64BIT_MEMORY_ACCESS)
u64 dv64;
for (; (ir + 32) <= limit; ir += 32) {
dv64 = get_unaligned((u64 *)ir);
dv64 |= get_unaligned((u64 *)ir + 1);
dv64 |= get_unaligned((u64 *)ir + 2);
dv64 |= get_unaligned((u64 *)ir + 3);
if (dv64)
break;
}
for (; (ir + 8) <= limit; ir += 8) {
dv64 = get_unaligned((u64 *)ir);
if (dv64) {
# if defined(__LITTLE_ENDIAN)
ir += __builtin_ctzll(dv64) >> 3;
# elif defined(__BIG_ENDIAN)
ir += __builtin_clzll(dv64) >> 3;
# else
# error "missing endian definition"
# endif
break;
}
}
#else
while ((ir < (const unsigned char *)
ALIGN((uintptr_t)ir, 4)) &&
(ir < limit) && (*ir == 0))
ir++;
if (IS_ALIGNED((uintptr_t)ir, 4)) {
for (; (ir + 4) <= limit; ir += 4) {
dv = *((u32 *)ir);
if (dv) {
# if defined(__LITTLE_ENDIAN)
ir += __builtin_ctz(dv) >> 3;
# elif defined(__BIG_ENDIAN)
ir += __builtin_clz(dv) >> 3;
# else
# error "missing endian definition"
# endif
break;
}
}
}
#endif
while (likely(ir < limit) && unlikely(*ir == 0))
ir++;
run_length = ir - ip;
if (run_length > MAX_ZERO_RUN_LENGTH)
run_length = MAX_ZERO_RUN_LENGTH;
} else {
t = ((dv * 0x1824429d) >> (32 - D_BITS)) & D_MASK;
m_pos = in + dict[t];
dict[t] = (lzo_dict_t) (ip - in);
if (unlikely(dv != get_unaligned_le32(m_pos)))
goto literal;
}
ii -= ti;
ti = 0;
t = ip - ii;
if (t != 0) {
if (t <= 3) {
op[*state_offset] |= t;
COPY4(op, ii);
op += t;
} else if (t <= 16) {
*op++ = (t - 3);
COPY8(op, ii);
COPY8(op + 8, ii + 8);
op += t;
} else {
if (t <= 18) {
*op++ = (t - 3);
} else {
size_t tt = t - 18;
*op++ = 0;
while (unlikely(tt > 255)) {
tt -= 255;
*op++ = 0;
}
*op++ = tt;
}
do {
COPY8(op, ii);
COPY8(op + 8, ii + 8);
op += 16;
ii += 16;
t -= 16;
} while (t >= 16);
if (t > 0) do {
*op++ = *ii++;
} while (--t > 0);
}
}
if (unlikely(run_length)) {
ip += run_length;
run_length -= MIN_ZERO_RUN_LENGTH;
put_unaligned_le32((run_length << 21) | 0xfffc18
| (run_length & 0x7), op);
op += 4;
run_length = 0;
*state_offset = -3;
goto finished_writing_instruction;
}
m_len = 4;
{
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(LZO_USE_CTZ64)
u64 v;
v = get_unaligned((const u64 *) (ip + m_len)) ^
get_unaligned((const u64 *) (m_pos + m_len));
if (unlikely(v == 0)) {
do {
m_len += 8;
v = get_unaligned((const u64 *) (ip + m_len)) ^
get_unaligned((const u64 *) (m_pos + m_len));
if (unlikely(ip + m_len >= ip_end))
goto m_len_done;
} while (v == 0);
}
# if defined(__LITTLE_ENDIAN)
m_len += (unsigned) __builtin_ctzll(v) / 8;
# elif defined(__BIG_ENDIAN)
m_len += (unsigned) __builtin_clzll(v) / 8;
# else
# error "missing endian definition"
# endif
#elif defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(LZO_USE_CTZ32)
u32 v;
v = get_unaligned((const u32 *) (ip + m_len)) ^
get_unaligned((const u32 *) (m_pos + m_len));
if (unlikely(v == 0)) {
do {
m_len += 4;
v = get_unaligned((const u32 *) (ip + m_len)) ^
get_unaligned((const u32 *) (m_pos + m_len));
if (v != 0)
break;
m_len += 4;
v = get_unaligned((const u32 *) (ip + m_len)) ^
get_unaligned((const u32 *) (m_pos + m_len));
if (unlikely(ip + m_len >= ip_end))
goto m_len_done;
} while (v == 0);
}
# if defined(__LITTLE_ENDIAN)
m_len += (unsigned) __builtin_ctz(v) / 8;
# elif defined(__BIG_ENDIAN)
m_len += (unsigned) __builtin_clz(v) / 8;
# else
# error "missing endian definition"
# endif
#else
if (unlikely(ip[m_len] == m_pos[m_len])) {
do {
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (ip[m_len] != m_pos[m_len])
break;
m_len += 1;
if (unlikely(ip + m_len >= ip_end))
goto m_len_done;
} while (ip[m_len] == m_pos[m_len]);
}
#endif
}
m_len_done:
m_off = ip - m_pos;
ip += m_len;
if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET) {
m_off -= 1;
*op++ = (((m_len - 1) << 5) | ((m_off & 7) << 2));
*op++ = (m_off >> 3);
} else if (m_off <= M3_MAX_OFFSET) {
m_off -= 1;
if (m_len <= M3_MAX_LEN)
*op++ = (M3_MARKER | (m_len - 2));
else {
m_len -= M3_MAX_LEN;
*op++ = M3_MARKER | 0;
while (unlikely(m_len > 255)) {
m_len -= 255;
*op++ = 0;
}
*op++ = (m_len);
}
*op++ = (m_off << 2);
*op++ = (m_off >> 6);
} else {
m_off -= 0x4000;
if (m_len <= M4_MAX_LEN)
*op++ = (M4_MARKER | ((m_off >> 11) & 8)
| (m_len - 2));
else {
if (unlikely(((m_off & 0x403f) == 0x403f)
&& (m_len >= 261)
&& (m_len <= 264))
&& likely(bitstream_version)) {
// Under lzo-rle, block copies
// for 261 <= length <= 264 and
// (distance & 0x80f3) == 0x80f3
// can result in ambiguous
// output. Adjust length
// to 260 to prevent ambiguity.
ip -= m_len - 260;
m_len = 260;
}
m_len -= M4_MAX_LEN;
*op++ = (M4_MARKER | ((m_off >> 11) & 8));
while (unlikely(m_len > 255)) {
m_len -= 255;
*op++ = 0;
}
*op++ = (m_len);
}
*op++ = (m_off << 2);
*op++ = (m_off >> 6);
}
*state_offset = -2;
finished_writing_instruction:
ii = ip;
goto next;
}
*out_len = op - out;
return in_end - (ii - ti);
}
int lzogeneric1x_1_compress(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len,
void *wrkmem, const unsigned char bitstream_version)
{
const unsigned char *ip = in;
unsigned char *op = out;
unsigned char *data_start;
size_t l = in_len;
size_t t = 0;
signed char state_offset = -2;
unsigned int m4_max_offset;
// LZO v0 will never write 17 as first byte (except for zero-length
// input), so this is used to version the bitstream
if (bitstream_version > 0) {
*op++ = 17;
*op++ = bitstream_version;
m4_max_offset = M4_MAX_OFFSET_V1;
} else {
m4_max_offset = M4_MAX_OFFSET_V0;
}
data_start = op;
while (l > 20) {
size_t ll = l <= (m4_max_offset + 1) ? l : (m4_max_offset + 1);
uintptr_t ll_end = (uintptr_t) ip + ll;
if ((ll_end + ((t + ll) >> 5)) <= ll_end)
break;
BUILD_BUG_ON(D_SIZE * sizeof(lzo_dict_t) > LZO1X_1_MEM_COMPRESS);
memset(wrkmem, 0, D_SIZE * sizeof(lzo_dict_t));
t = lzo1x_1_do_compress(ip, ll, op, out_len, t, wrkmem,
&state_offset, bitstream_version);
ip += ll;
op += *out_len;
l -= ll;
}
t += l;
if (t > 0) {
const unsigned char *ii = in + in_len - t;
if (op == data_start && t <= 238) {
*op++ = (17 + t);
} else if (t <= 3) {
op[state_offset] |= t;
} else if (t <= 18) {
*op++ = (t - 3);
} else {
size_t tt = t - 18;
*op++ = 0;
while (tt > 255) {
tt -= 255;
*op++ = 0;
}
*op++ = tt;
}
if (t >= 16) do {
COPY8(op, ii);
COPY8(op + 8, ii + 8);
op += 16;
ii += 16;
t -= 16;
} while (t >= 16);
if (t > 0) do {
*op++ = *ii++;
} while (--t > 0);
}
*op++ = M4_MARKER | 1;
*op++ = 0;
*op++ = 0;
*out_len = op - out;
return LZO_E_OK;
}
int lzo1x_1_compress(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len,
void *wrkmem)
{
return lzogeneric1x_1_compress(in, in_len, out, out_len, wrkmem, 0);
}
int lzorle1x_1_compress(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len,
void *wrkmem)
{
return lzogeneric1x_1_compress(in, in_len, out, out_len,
wrkmem, LZO_VERSION);
}
EXPORT_SYMBOL_GPL(lzo1x_1_compress);
EXPORT_SYMBOL_GPL(lzorle1x_1_compress);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LZO1X-1 Compressor");
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