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Subject: Re: [PATCH 5.4 031/184] modules: inherit TAINT_PROPRIETARY_MODULE
From:   Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
Cc:     stable@vger.kernel.org, Daniel Vetter <daniel.vetter@ffwll.ch>,
        Christoph Hellwig <hch@lst.de>, Jessica Yu <jeyu@kernel.org>
References: <20210510101950.200777181@linuxfoundation.org>
 <20210510101951.249384110@linuxfoundation.org>
 <8edc6f45-6c42-19c7-6f40-6f1a49cc685b@canonical.com>
Message-ID: <08a2e600-74cf-dbf8-1ecc-777ff65e06b0@canonical.com>
Date:   Fri, 18 Jun 2021 10:59:50 +0200
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On 18/06/2021 10:57, Krzysztof Kozlowski wrote:
> On 10/05/2021 12:18, Greg Kroah-Hartman wrote:
>> From: Christoph Hellwig <hch@lst.de>
>>
>> commit 262e6ae7081df304fc625cf368d5c2cbba2bb991 upstream.
>>
>> If a TAINT_PROPRIETARY_MODULE exports symbol, inherit the taint flag
>> for all modules importing these symbols, and don't allow loading
>> symbols from TAINT_PROPRIETARY_MODULE modules if the module previously
>> imported gplonly symbols.  Add a anti-circumvention devices so people
>> don't accidentally get themselves into trouble this way.
>>
>> Comment from Greg:
>>   "Ah, the proven-to-be-illegal "GPL Condom" defense :)"
> 
> Patch got in to stable, so my comments are quite late, but can someone
> explain me - how this is a stable material? What specific, real bug that
> bothers people, is being fixed here? Or maybe it fixes serious issue
> reported by a user of distribution kernel? IOW, how does this match
> stable kernel rules at all?
> 
> For sure it breaks some out-of-tree modules already present and used by
> customers of downstream stable kernels. Therefore I wonder what is the
> bug fixed here, so the breakage and annoyance of stable users is justified.

And for the record I am not talking about this patch only. I am asking
also what serious or real bug is being fixed by:
"modules: mark find_symbol static
find_symbol is only used in module.c."

I would be really happy to extend my knowledge about real bugs faced by
people, where the fix is to un-export unused symbol. It must have been
very interesting, real bug bothering people. :)


Best regards,
Krzysztof