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

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Message-ID: <alpine.DEB.2.21.2110291708040.20378@gnbcxd0088.gnb.st.com>
Date:   Fri, 29 Oct 2021 17:21:24 +0200
From:   Nicolas Toromanoff <nicolas.toromanoff@...s.st.com>
To:     Marek Vasut <marex@...x.de>
CC:     Nicolas Toromanoff <nicolas.toromanoff@...s.st.com>,
        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 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

while(true) do ; modprobe stm32-cryp && modprobe -r stm32-cryp ; done

ran a whole day without a crash, nor a detected error.

-- 
Nicolas.