diff --git a/tests/image-fuzzer/qcow2/fuzz.py b/tests/image-fuzzer/qcow2/fuzz.py
new file mode 100644
index 0000000..a53c84f
--- /dev/null
+++ b/tests/image-fuzzer/qcow2/fuzz.py
@@ -0,0 +1,327 @@
+# Fuzzing functions for qcow2 fields
+#
+# Copyright (C) 2014 Maria Kustova <maria.k@catit.be>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import random
+
+
+UINT8 = 0xff
+UINT32 = 0xffffffff
+UINT64 = 0xffffffffffffffff
+# Most significant bit orders
+UINT32_M = 31
+UINT64_M = 63
+# Fuzz vectors
+UINT8_V = [0, 0x10, UINT8/4, UINT8/2 - 1, UINT8/2, UINT8/2 + 1, UINT8 - 1,
+           UINT8]
+UINT32_V = [0, 0x100, 0x1000, 0x10000, 0x100000, UINT32/4, UINT32/2 - 1,
+            UINT32/2, UINT32/2 + 1, UINT32 - 1, UINT32]
+UINT64_V = UINT32_V + [0x1000000, 0x10000000, 0x100000000, UINT64/4,
+                       UINT64/2 - 1, UINT64/2, UINT64/2 + 1, UINT64 - 1,
+                       UINT64]
+STRING_V = ['%s%p%x%d', '.1024d', '%.2049d', '%p%p%p%p', '%x%x%x%x',
+            '%d%d%d%d', '%s%s%s%s', '%99999999999s', '%08x', '%%20d', '%%20n',
+            '%%20x', '%%20s', '%s%s%s%s%s%s%s%s%s%s', '%p%p%p%p%p%p%p%p%p%p',
+            '%#0123456x%08x%x%s%p%d%n%o%u%c%h%l%q%j%z%Z%t%i%e%g%f%a%C%S%08x%%',
+            '%s x 129', '%x x 257']
+
+
+def random_from_intervals(intervals):
+    """Select a random integer number from the list of specified intervals.
+
+    Each interval is a tuple of lower and upper limits of the interval. The
+    limits are included. Intervals in a list should not overlap.
+    """
+    total = reduce(lambda x, y: x + y[1] - y[0] + 1, intervals, 0)
+    r = random.randint(0, total - 1) + intervals[0][0]
+    for x in zip(intervals, intervals[1:]):
+        r = r + (r > x[0][1]) * (x[1][0] - x[0][1] - 1)
+    return r
+
+
+def random_bits(bit_ranges):
+    """Generate random binary mask with ones in the specified bit ranges.
+
+    Each bit_ranges is a list of tuples of lower and upper limits of bit
+    positions will be fuzzed. The limits are included. Random amount of bits
+    in range limits will be set to ones. The mask is returned in decimal
+    integer format.
+    """
+    bit_numbers = []
+    # Select random amount of random positions in bit_ranges
+    for rng in bit_ranges:
+        bit_numbers += random.sample(range(rng[0], rng[1] + 1),
+                                     random.randint(0, rng[1] - rng[0] + 1))
+    val = 0
+    # Set bits on selected positions to ones
+    for bit in bit_numbers:
+        val |= 1 << bit
+    return val
+
+
+def truncate_string(strings, length):
+    """Return strings truncated to specified length."""
+    if type(strings) == list:
+        return [s[:length] for s in strings]
+    else:
+        return strings[:length]
+
+
+def validator(current, pick, choices):
+    """Return a value not equal to the current selected by the pick
+    function from choices.
+    """
+    while True:
+        val = pick(choices)
+        if not val == current:
+            return val
+
+
+def int_validator(current, intervals):
+    """Return a random value from intervals not equal to the current.
+
+    This function is useful for selection from valid values except current one.
+    """
+    return validator(current, random_from_intervals, intervals)
+
+
+def bit_validator(current, bit_ranges):
+    """Return a random bit mask not equal to the current.
+
+    This function is useful for selection from valid values except current one.
+    """
+    return validator(current, random_bits, bit_ranges)
+
+
+def string_validator(current, strings):
+    """Return a random string value from the list not equal to the current.
+
+    This function is useful for selection from valid values except current one.
+    """
+    return validator(current, random.choice, strings)
+
+
+def selector(current, constraints, validate=int_validator):
+    """Select one value from all defined by constraints.
+
+    Each constraint produces one random value satisfying to it. The function
+    randomly selects one value satisfying at least one constraint (depending on
+    constraints overlaps).
+    """
+    def iter_validate(c):
+        """Apply validate() only to constraints represented as lists.
+
+        This auxiliary function replaces short circuit conditions not supported
+        in Python 2.4
+        """
+        if type(c) == list:
+            return validate(current, c)
+        else:
+            return c
+
+    fuzz_values = [iter_validate(c) for c in constraints]
+    # Remove current for cases it's implicitly specified in constraints
+    # Duplicate validator functionality to prevent decreasing of probability
+    # to get one of allowable values
+    # TODO: remove validators after implementation of intelligent selection
+    # of fields will be fuzzed
+    try:
+        fuzz_values.remove(current)
+    except ValueError:
+        pass
+    return random.choice(fuzz_values)
+
+
+def magic(current):
+    """Fuzz magic header field.
+
+    The function just returns the current magic value and provides uniformity
+    of calls for all fuzzing functions.
+    """
+    return current
+
+
+def version(current):
+    """Fuzz version header field."""
+    constraints = UINT32_V + [
+        [(2, 3)],  # correct values
+        [(0, 1), (4, UINT32)]
+    ]
+    return selector(current, constraints)
+
+
+def backing_file_offset(current):
+    """Fuzz backing file offset header field."""
+    constraints = UINT64_V
+    return selector(current, constraints)
+
+
+def backing_file_size(current):
+    """Fuzz backing file size header field."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def cluster_bits(current):
+    """Fuzz cluster bits header field."""
+    constraints = UINT32_V + [
+        [(9, 20)],  # correct values
+        [(0, 9), (20, UINT32)]
+    ]
+    return selector(current, constraints)
+
+
+def size(current):
+    """Fuzz image size header field."""
+    constraints = UINT64_V
+    return selector(current, constraints)
+
+
+def crypt_method(current):
+    """Fuzz crypt method header field."""
+    constraints = UINT32_V + [
+        1,
+        [(2, UINT32)]
+    ]
+    return selector(current, constraints)
+
+
+def l1_size(current):
+    """Fuzz L1 table size header field."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def l1_table_offset(current):
+    """Fuzz L1 table offset header field."""
+    constraints = UINT64_V
+    return selector(current, constraints)
+
+
+def refcount_table_offset(current):
+    """Fuzz refcount table offset header field."""
+    constraints = UINT64_V
+    return selector(current, constraints)
+
+
+def refcount_table_clusters(current):
+    """Fuzz refcount table clusters header field."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def nb_snapshots(current):
+    """Fuzz number of snapshots header field."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def snapshots_offset(current):
+    """Fuzz snapshots offset header field."""
+    constraints = UINT64_V
+    return selector(current, constraints)
+
+
+def incompatible_features(current):
+    """Fuzz incompatible features header field."""
+    constraints = [
+        [(0, 1)],  # allowable values
+        [(0, UINT64_M)]
+    ]
+    return selector(current, constraints, bit_validator)
+
+
+def compatible_features(current):
+    """Fuzz compatible features header field."""
+    constraints = [
+        [(0, UINT64_M)]
+    ]
+    return selector(current, constraints, bit_validator)
+
+
+def autoclear_features(current):
+    """Fuzz autoclear features header field."""
+    constraints = [
+        [(0, UINT64_M)]
+    ]
+    return selector(current, constraints, bit_validator)
+
+
+def refcount_order(current):
+    """Fuzz number of refcount order header field."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def header_length(current):
+    """Fuzz number of refcount order header field."""
+    constraints = UINT32_V + [
+        72,
+        104,
+        [(0, UINT32)]
+    ]
+    return selector(current, constraints)
+
+
+def bf_name(current):
+    """Fuzz the backing file name."""
+    constraints = [
+        truncate_string(STRING_V, len(current))
+    ]
+    return selector(current, constraints, string_validator)
+
+
+def ext_magic(current):
+    """Fuzz magic field of a header extension."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def ext_length(current):
+    """Fuzz length field of a header extension."""
+    constraints = UINT32_V
+    return selector(current, constraints)
+
+
+def bf_format(current):
+    """Fuzz backing file format in the corresponding header extension."""
+    constraints = [
+        truncate_string(STRING_V, len(current)),
+        truncate_string(STRING_V, (len(current) + 7) & ~7)  # Fuzz padding
+    ]
+    return selector(current, constraints, string_validator)
+
+
+def feature_type(current):
+    """Fuzz feature type field of a feature name table header extension."""
+    constraints = UINT8_V
+    return selector(current, constraints)
+
+
+def feature_bit_number(current):
+    """Fuzz bit number field of a feature name table header extension."""
+    constraints = UINT8_V
+    return selector(current, constraints)
+
+
+def feature_name(current):
+    """Fuzz feature name field of a feature name table header extension."""
+    constraints = [
+        truncate_string(STRING_V, len(current)),
+        truncate_string(STRING_V, 46)  # Fuzz padding (field length = 46)
+    ]
+    return selector(current, constraints, string_validator)
