From 33706f99ce56e178b058b180661aacbea2e79ce9 Mon Sep 17 00:00:00 2001 From: Thomas Haller Date: Fri, 18 Aug 2023 11:40:39 +0200 Subject: py: fix exception during cleanup of half-initialized Nftables When we create a Nftables instance against an older library version, we might not find a symbol and fail with an exception when initializing the context object. Then, __del__() is still called, but resulting in a second exception because self.__ctx is not set. Avoid that second exception. $ python -c 'import nftables; nftables.Nftables()' Traceback (most recent call last): File "", line 1, in File "/data/src/nftables/py/nftables.py", line 90, in __init__ self.nft_ctx_input_get_flags = lib.nft_ctx_input_get_flags ^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/lib64/python3.11/ctypes/__init__.py", line 389, in __getattr__ func = self.__getitem__(name) ^^^^^^^^^^^^^^^^^^^^^^ File "/usr/lib64/python3.11/ctypes/__init__.py", line 394, in __getitem__ func = self._FuncPtr((name_or_ordinal, self)) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ AttributeError: /lib64/libnftables.so.1: undefined symbol: nft_ctx_input_get_flags Exception ignored in: Traceback (most recent call last): File "/data/src/nftables/py/nftables.py", line 166, in __del__ self.nft_ctx_free(self.__ctx) ^^^^^^^^^^^^^^^^^ AttributeError: 'Nftables' object has no attribute 'nft_ctx_free' Signed-off-by: Thomas Haller Reviewed-by: Phil Sutter Signed-off-by: Pablo Neira Ayuso --- py/src/nftables.py | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'py/src/nftables.py') diff --git a/py/src/nftables.py b/py/src/nftables.py index 68fcd7dd..b1186781 100644 --- a/py/src/nftables.py +++ b/py/src/nftables.py @@ -74,6 +74,8 @@ class Nftables: is requested from the library and buffering of output and error streams is turned on. """ + self.__ctx = None + lib = cdll.LoadLibrary(sofile) ### API function definitions @@ -150,7 +152,9 @@ class Nftables: self.nft_ctx_buffer_error(self.__ctx) def __del__(self): - self.nft_ctx_free(self.__ctx) + if self.__ctx is not None: + self.nft_ctx_free(self.__ctx) + self.__ctx = None def __get_output_flag(self, name): flag = self.output_flags[name] -- cgit v1.2.3