linux-kernel - Re: [PATCH v9 4/5] tpm: Add a driver for Loongson TPM device

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Message-ID: <aB0MW6kQJHYW9LWi@kernel.org>
Date: Thu, 8 May 2025 22:56:11 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: Qunqin Zhao <zhaoqunqin@...ngson.cn>, lee@...nel.org,
	herbert@...dor.apana.org.au, davem@...emloft.net, peterhuewe@....de,
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
	linux-crypto@...r.kernel.org, jgg@...pe.ca,
	linux-integrity@...r.kernel.org, pmenzel@...gen.mpg.de,
	Yinggang Gu <guyinggang@...ngson.cn>,
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH v9 4/5] tpm: Add a driver for Loongson TPM device

On Tue, May 06, 2025 at 04:13:04PM +0200, Stefano Garzarella wrote:
> > +static int tpm_loongson_recv(struct tpm_chip *chip, u8 *buf, size_t count)
> > +{
> > +	struct loongson_se_engine *tpm_engine = dev_get_drvdata(&chip->dev);
> > +	struct tpm_loongson_cmd *cmd_ret = tpm_engine->command_ret;
> > +
> > +	memcpy(buf, tpm_engine->data_buffer, cmd_ret->data_len);
> 
> Should we limit the memcpy to `count`?
> 
> I mean, can happen that `count` is less than `cmd_ret->data_len`?

It should check-and-fail:

	if (cmd_ret->data_len > count)
		return -EIO;

Thanks, this was a good catch.

> 
> Thanks,
> Stefano

BR, Jarkko