Python bindings crash when more than one Nftables is instantiated

Python bindings crash when more than one Nftables is instantiated

[Eugene Crosser]

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Hello,

it seems to me that this should not be happening. Use case is not as
pathological as it may seem: your program may be using different third party
modules, each of them instantiate `Nftables` interface.

$ sudo python
[sudo] password for echerkashin:
Python 3.9.7 (default, Sep  3 2021, 06:18:44)
[GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from nftables import Nftables
>>> n1=Nftables()
>>> n2=Nftables()
>>> <Ctrl-D>
double free or corruption (top)
Aborted

Note that it happens on exit (possibly on the second call to __del__()).

nftables v0.9.9

Regards,

Eugene


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Re: Python bindings crash when more than one Nftables is instantiated

[Pablo Neira Ayuso]

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On Tue, Sep 14, 2021 at 07:46:16PM +0200, Eugene Crosser wrote:
> Hello,
> 
> it seems to me that this should not be happening. Use case is not as
> pathological as it may seem: your program may be using different third party
> modules, each of them instantiate `Nftables` interface.
> 
> $ sudo python
> [sudo] password for echerkashin:
> Python 3.9.7 (default, Sep  3 2021, 06:18:44)
> [GCC 11.2.0] on linux
> Type "help", "copyright", "credits" or "license" for more information.
> >>> from nftables import Nftables
> >>> n1=Nftables()
> >>> n2=Nftables()
> >>> <Ctrl-D>
> double free or corruption (top)
> Aborted
> 
> Note that it happens on exit (possibly on the second call to __del__()).
> 
> nftables v0.9.9

Upstream fix:

http://git.netfilter.org/nftables/commit/?id=b85769f9397c72ab62387ccc5b7a66d0c3ff5f21

Thanks for reporting.

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