diff options
Diffstat (limited to 'lib/lzo/lzo1x_decompress_safe.c')
| -rw-r--r-- | lib/lzo/lzo1x_decompress_safe.c | 103 |
1 files changed, 57 insertions, 46 deletions
diff --git a/lib/lzo/lzo1x_decompress_safe.c b/lib/lzo/lzo1x_decompress_safe.c index 8563081e8da..a1c387f6afb 100644 --- a/lib/lzo/lzo1x_decompress_safe.c +++ b/lib/lzo/lzo1x_decompress_safe.c @@ -19,31 +19,21 @@ #include <linux/lzo.h> #include "lzodefs.h" -#define HAVE_IP(t, x) \ - (((size_t)(ip_end - ip) >= (size_t)(t + x)) && \ - (((t + x) >= t) && ((t + x) >= x))) +#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 -#define HAVE_OP(t, x) \ - (((size_t)(op_end - op) >= (size_t)(t + x)) && \ - (((t + x) >= t) && ((t + x) >= x))) - -#define NEED_IP(t, x) \ - do { \ - if (!HAVE_IP(t, x)) \ - goto input_overrun; \ - } while (0) - -#define NEED_OP(t, x) \ - do { \ - if (!HAVE_OP(t, x)) \ - goto output_overrun; \ - } while (0) - -#define TEST_LB(m_pos) \ - do { \ - if ((m_pos) < out) \ - goto lookbehind_overrun; \ - } while (0) +/* 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) @@ -75,17 +65,24 @@ int lzo1x_decompress_safe(const unsigned char *in, size_t in_len, if (t < 16) { if (likely(state == 0)) { if (unlikely(t == 0)) { + size_t offset; + const unsigned char *ip_last = ip; + while (unlikely(*ip == 0)) { - t += 255; ip++; - NEED_IP(1, 0); + NEED_IP(1); } - t += 15 + *ip++; + 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))) { + if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) { const unsigned char *ie = ip + t; unsigned char *oe = op + t; do { @@ -101,8 +98,8 @@ copy_literal_run: } else #endif { - NEED_OP(t, 0); - NEED_IP(t, 3); + NEED_OP(t); + NEED_IP(t + 3); do { *op++ = *ip++; } while (--t > 0); @@ -115,7 +112,7 @@ copy_literal_run: m_pos -= t >> 2; m_pos -= *ip++ << 2; TEST_LB(m_pos); - NEED_OP(2, 0); + NEED_OP(2); op[0] = m_pos[0]; op[1] = m_pos[1]; op += 2; @@ -136,13 +133,20 @@ copy_literal_run: } 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)) { - t += 255; ip++; - NEED_IP(1, 0); + NEED_IP(1); } - t += 31 + *ip++; - NEED_IP(2, 0); + 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); @@ -154,13 +158,20 @@ copy_literal_run: 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)) { - t += 255; ip++; - NEED_IP(1, 0); + NEED_IP(1); } - t += 7 + *ip++; - NEED_IP(2, 0); + 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; @@ -174,7 +185,7 @@ copy_literal_run: #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) if (op - m_pos >= 8) { unsigned char *oe = op + t; - if (likely(HAVE_OP(t, 15))) { + if (likely(HAVE_OP(t + 15))) { do { COPY8(op, m_pos); op += 8; @@ -184,7 +195,7 @@ copy_literal_run: m_pos += 8; } while (op < oe); op = oe; - if (HAVE_IP(6, 0)) { + if (HAVE_IP(6)) { state = next; COPY4(op, ip); op += next; @@ -192,7 +203,7 @@ copy_literal_run: continue; } } else { - NEED_OP(t, 0); + NEED_OP(t); do { *op++ = *m_pos++; } while (op < oe); @@ -201,7 +212,7 @@ copy_literal_run: #endif { unsigned char *oe = op + t; - NEED_OP(t, 0); + NEED_OP(t); op[0] = m_pos[0]; op[1] = m_pos[1]; op += 2; @@ -214,15 +225,15 @@ match_next: state = next; t = next; #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) - if (likely(HAVE_IP(6, 0) && HAVE_OP(4, 0))) { + if (likely(HAVE_IP(6) && HAVE_OP(4))) { COPY4(op, ip); op += t; ip += t; } else #endif { - NEED_IP(t, 3); - NEED_OP(t, 0); + NEED_IP(t + 3); + NEED_OP(t); while (t > 0) { *op++ = *ip++; t--; |