netdev - Re: [PATCH net] selftests: net: fix wrong boolean evaluation in __exit_

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <94e91bcc-6257-4edd-bc61-eabbfd547110@nvidia.com>
Date: Wed, 21 Jan 2026 09:11:40 +0200
From: Gal Pressman <gal@...dia.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, netdev@...r.kernel.org,
 Simon Horman <horms@...nel.org>, Shuah Khan <shuah@...nel.org>,
 Joe Damato <joe@...a.to>, Stanislav Fomichev <sdf@...ichev.me>,
 linux-kselftest@...r.kernel.org, Nimrod Oren <noren@...dia.com>
Subject: Re: [PATCH net] selftests: net: fix wrong boolean evaluation in
 __exit__

On 21/01/2026 1:44, Jakub Kicinski wrote:
> On Tue, 20 Jan 2026 14:47:33 +0200 Gal Pressman wrote:
>> The __exit__ method receives ex_type as the exception class when an
>> exception occurs. The previous code used implicit boolean evaluation:
>>
>>     terminate = self.terminate or (self._exit_wait and ex_type)
>>                                                    ^^^^^^^^^^^
>>
>> In Python, the and operator can be used with non-boolean values, but it
>> does not always return a boolean result.
>>
>> This is probably not what we want, because 'self._exit_wait and ex_type'
>> could return the actual ex_type value (the exception class) rather than
>> a boolean True when an exception occurs.
>>
>> Use explicit `ex_type is not None` check to properly evaluate whether
>> an exception occurred, returning a boolean result.
> 
> Sure, the checkers complain about this, but I don't see an actual bug
> here. bool(terminate) must evaluate correctly, we don't compare it
> to True or False explicitly.
> 
> To be clear - the patch LGTM, I'm just not connecting the dots on why
> its a fix at this stage.

Right, the code probably works regardless of this fix.
The reason I submitted this as a fix is because surely there was no
intention for 'terminate' to be non-boolean.

Take the patch to net-next instead?

BTW, I encountered this issue while debugging some tests and dumping
various states, the value of 'terminate' confused me.