linux-kernel - Re: [PATCH 4/8] crypto: stm32/cryp

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Date:   Fri, 29 Oct 2021 18:48:43 +0200
From:   Marek Vasut <marex@...x.de>
To:     Nicolas Toromanoff <nicolas.toromanoff@...s.st.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-crypto@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8] crypto: stm32/cryp - fix race condition

On 10/29/21 5:21 PM, Nicolas Toromanoff wrote:
> On Fri, 29 Oct 2021, Marek Vasut wrote:
> 
>> On 10/29/21 3:54 PM, Nicolas Toromanoff wrote:
>>> Erase key before finalizing request.
>>> Fixes: 9e054ec21ef8 ("crypto: stm32 - Support for STM32 CRYP crypto 
>>> module")
>>
>> Can you be a bit more specific in your commit messages ? That applies 
>> to the entire patchset. It is absolutely impossible to tell what race 
>> is fixed here or why it is fixed by exactly this change. This applies 
>> to the entire series.
> 
> I'll send a v2 with better commit messages.
> 
> for this specific patch:
> We reset the saved key before the crypto_finalize_*() call. Otherwise a 
> still pending crypto action could be ran with a wrong key = {0};
> 
>> And while I am at it, does the CRYP finally pass at least the most 
>> basic kernel boot time crypto tests or does running those still 
>> overwrite kernel memory and/or completely crash or lock up the machine ?
> 
> All extra tests (finally) pass.
> 
> With a kernel config :
>    # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
>    CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y
>    CONFIG_CRYPTO_DEV_STM32_CRYP=m

Can you also do a boot test with CRYP compiled into the kernel ?
I recall that is how the original bug was reported -- the machine 
crashed completely on boot even before reaching userspace, or the kernel 
crashed on memory corruption before reaching userspace.