diff options
Diffstat (limited to 'lib/lzo/lzo1x_decompress_safe.c')
| -rw-r--r-- | lib/lzo/lzo1x_decompress_safe.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/lib/lzo/lzo1x_decompress_safe.c b/lib/lzo/lzo1x_decompress_safe.c new file mode 100644 index 000000000..a1c387f6a --- /dev/null +++ b/lib/lzo/lzo1x_decompress_safe.c @@ -0,0 +1,268 @@ +/* + * 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; + + op = out; + ip = in; + + if (unlikely(in_len < 3)) + goto input_overrun; + 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 { + 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 |