linux-kernel - Re: [PATCH v3 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC

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

Message-ID: <Y70WgbySlio6cjew@gondor.apana.org.au>
Date:   Tue, 10 Jan 2023 15:40:49 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Jia Jie Ho <jiajie.ho@...rfivetech.com>
Cc:     Olivia Mackall <olivia@...enic.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-crypto@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v3 2/3] hwrng: starfive - Add TRNG driver for StarFive SoC

On Tue, Jan 10, 2023 at 12:52:48AM +0800, Jia Jie Ho wrote:
>
> +static irqreturn_t starfive_trng_irq(int irq, void *priv)
> +{
> +	u32 status;
> +	struct starfive_trng *trng = (struct starfive_trng *)priv;
> +
> +	status = readl(trng->base + STARFIVE_ISTAT);
> +	if (status & STARFIVE_ISTAT_RAND_RDY) {
> +		writel(STARFIVE_ISTAT_RAND_RDY, trng->base + STARFIVE_ISTAT);
> +		complete(&trng->random_done);
> +	}
> +
> +	if (status & STARFIVE_ISTAT_SEED_DONE) {
> +		writel(STARFIVE_ISTAT_SEED_DONE, trng->base + STARFIVE_ISTAT);
> +		complete(&trng->reseed_done);
> +	}
> +
> +	if (status & STARFIVE_ISTAT_LFSR_LOCKUP) {
> +		writel(STARFIVE_ISTAT_LFSR_LOCKUP, trng->base + STARFIVE_ISTAT);
> +		/* SEU occurred, reseeding required*/
> +		writel(STARFIVE_CTRL_EXEC_RANDRESEED, trng->base + STARFIVE_CTRL);

This could occur at the same time as a GENE_RANDNUM write so perhaps
you should add some locking?

> +	ret = devm_request_irq(&pdev->dev, irq, starfive_trng_irq, 0, pdev->name,
> +			       (void *)trng);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, irq,
> +				     "Failed to register interrupt handler\n");

...

> +	init_completion(&trng->random_done);
> +	init_completion(&trng->reseed_done);

These completion initialisations should be moved above the IRQ
registration because you should always be prepared to get spurious
interrupts.

Otherwise the patch looks good.

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt