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BPF filter: fix memory leak #4872

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BPF filter: fix memory leak #4872

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4 changes: 3 additions & 1 deletion scapy/arch/bpf/core.py
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@
import struct

from scapy.arch.bpf.consts import BIOCSETF, BIOCSETIF
from scapy.arch.common import compile_filter
from scapy.arch.common import compile_filter, free_filter
from scapy.config import conf
from scapy.consts import LINUX
from scapy.error import Scapy_Exception
Expand Down Expand Up @@ -76,6 +76,8 @@ def attach_filter(fd, bpf_filter, iface):
ret = fcntl.ioctl(fd, BIOCSETF, bp)
if ret < 0:
raise Scapy_Exception("Can't attach the BPF filter !")
# Free
free_filter(bp)


def in6_getifaddr():
Expand Down
8 changes: 8 additions & 0 deletions scapy/arch/common.py
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,14 @@ def compile_filter(filter_exp, # type: str
return bpf


def free_filter(bp: bpf_program) -> None:
"""
Free a bpf_program created with compile_filter
"""
from scapy.libs.winpcapy import pcap_freecode
pcap_freecode(ctypes.byref(bp))


#######
# DNS #
#######
Expand Down
9 changes: 5 additions & 4 deletions scapy/arch/linux/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@

from scapy.compat import raw
from scapy.consts import LINUX
from scapy.arch.common import compile_filter
from scapy.arch.common import compile_filter, free_filter
from scapy.config import conf
from scapy.data import MTU, ETH_P_ALL, SOL_PACKET, SO_ATTACH_FILTER, \
SO_TIMESTAMPNS
Expand Down Expand Up @@ -130,13 +130,14 @@ def attach_filter(sock, bpf_filter, iface):
if conf.use_pypy and sys.pypy_version_info <= (7, 3, 2): # type: ignore
# PyPy < 7.3.2 has a broken behavior
# https://foss.heptapod.net/pypy/pypy/-/issues/3298
bp = struct.pack( # type: ignore
fp = struct.pack(
'HL',
bp.bf_len, ctypes.addressof(bp.bf_insns.contents)
)
else:
bp = sock_fprog(bp.bf_len, bp.bf_insns) # type: ignore
sock.setsockopt(socket.SOL_SOCKET, SO_ATTACH_FILTER, bp)
fp = sock_fprog(bp.bf_len, bp.bf_insns) # type: ignore
sock.setsockopt(socket.SOL_SOCKET, SO_ATTACH_FILTER, fp)
free_filter(bp)


def set_promisc(s, iff, val=1):
Expand Down