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Message-ID: <d9aae981-ea93-418e-8c98-94eb27f4a80d@leemhuis.info>
Date: Wed, 20 Mar 2024 16:13:39 +0100
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Subject: Re: [PATCH] crypto: af_alg - Disallow multiple in-flight AIO requests
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From: "Linux regression tracking (Thorsten Leemhuis)"
 <regressions@leemhuis.info>
To: Ralph Siemsen <ralph.siemsen@linaro.org>
Cc: Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
 Greg KH <gregkh@linuxfoundation.org>,
 "stable@vger.kernel.org" <stable@vger.kernel.org>,
 Sasha Levin <sashal@kernel.org>, Herbert Xu <herbert@gondor.apana.org.au>,
 Linux kernel regressions list <regressions@lists.linux.dev>
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 Linux regressions mailing list <regressions@lists.linux.dev>
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 <20240315175529.GA268782@maple.netwinder.org>
 <256024ba-c889-4400-a7cd-002291e64ad5@leemhuis.info>
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On 20.03.24 15:54, Linux regression tracking (Thorsten Leemhuis) wrote:
> [CCing the stable team, as it looks like two prerequisite changes for a
> patch already applied are missing in at least 4.19.y]

Argh, race condition, it's now 15 minutes later and I by chance just saw
that Ralph about about 45 minutes ago took action as well an brought the
issue to the stable teams attention:
https://lore.kernel.org/all/20240320143143.1643630-1-ralph.siemsen@linaro.org/

Guess its best if everyone ignored my earlier mail. Sorry, bad timing,
happens.

Ciao, Thorsten

> On 15.03.24 18:55, Ralph Siemsen wrote:
>>
>> I have found a regression in userspace behaviour after this patch was
>> merged into the 4.19.y kernel. The fix seems to involve backporting a
>> few more changes. Could you review details below and confirm if this is
>> the right approach?
> 
> FWIW, developers are totally free to not care about stable and longterm
> kernels series. Not sure if Herbert is among those developers, but it
> might explain why there is no reply yet. That's why I CCed the stable
> maintainers, strictly speaking they are responsible.
> 
>> On Tue, Nov 28, 2023 at 04:25:49PM +0800, Herbert Xu wrote:
>>> Having multiple in-flight AIO requests results in unpredictable
>>> output because they all share the same IV.  Fix this by only allowing
>>> one request at a time.
>> [...]
>> This change got backported on the 4.19 kernel in January:
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=19af0310c8767c993f2a5d5261e4df3f9f465ce1
>>
>> Since then, I am seeCiao, ing a regression in a simple openssl encoding test:
>>
>> openssl enc -k mysecret -aes-256-cbc -in plain.txt -out cipher.txt
>> -engine afalg
>>
>> It fails intermittently with the message "error writing to file", but
>> this error is a bit misleading, the actual problem is that the kernel
>> returns -16 (EBUSY) on the encoding operation.
>>
>> This happens only in 4.19, and not under 5.10. The patch seems correct,
>> however it seems we are missing a couple of other patches on 4.19:
>>
>> f3c802a1f3001 crypto: algif_aead - Only wake up when ctx->more is zero
>> 21dfbcd1f5cbf crypto: algif_aead - fix uninitialized ctx->init
>>
>> I was able to cherry-pick those into 4.19.y, with just a minor conflict
>> in one case. With those applied, the openssl command no longer fails.
> 
> Some feedback here from Herbert would of course be splendid, but maybe
> your tests are all the stable team needs to pick those up for a future
> 4.19.y release.
> 
>> I suspect similar changes would be needed also in 5.4 kernel, however I
>> neither checked that, nor have I run any tests on that version.
> 
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.
> 
>