#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)
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 {
} else
#endif
{
- NEED_OP(t, 0);
- NEED_IP(t, 3);
+ NEED_OP(t);
+ NEED_IP(t + 3);
do {
*op++ = *ip++;
} while (--t > 0);
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;
} 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);
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;
#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;
m_pos += 8;
} while (op < oe);
op = oe;
- if (HAVE_IP(6, 0)) {
+ if (HAVE_IP(6)) {
state = next;
COPY4(op, ip);
op += next;
continue;
}
} else {
- NEED_OP(t, 0);
+ NEED_OP(t);
do {
*op++ = *m_pos++;
} while (op < oe);
#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;
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--;
git.openpandora.org / pandora-kernel.git / blobdiff