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Date:   Wed, 03 May 2023 14:29:40 +0300
Message-Id: <CSCLWCIOO1AL.3844034WWD0MT@suppilovahvero>
Subject: Re: [PATCH v4 04/13] tpm: add buffer handling for TPM2B types
From:   "Jarkko Sakkinen" <jarkko@kernel.org>
To:     "Stefan Berger" <stefanb@linux.ibm.com>,
        "James Bottomley" <James.Bottomley@HansenPartnership.com>,
        <linux-integrity@vger.kernel.org>
Cc:     <keyrings@vger.kernel.org>, "Ard Biesheuvel" <ardb@kernel.org>
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On Tue May 2, 2023 at 6:43 PM EEST, Stefan Berger wrote:
> > +void tpm_buf_append_2b(struct tpm_buf *buf, struct tpm_buf *tpm2b)
> > +{
> > +	u16 len =3D tpm_buf_length(tpm2b);
> > +
>
> if (tpm2b->flags & TPM_BUF_OVERFLOW) {
>      buf->flags |=3D TPM_BUF_OVERFLOW;
>      return;
> }
>
> > +	tpm_buf_append_u16(buf, len);
> > +	tpm_buf_append(buf, tpm_buf_data(tpm2b), len);
>
>
> > +	/* clear the buf for reuse */
> > +	tpm_buf_reset_int(tpm2b);

This should only append. Unpredictable side-effect like this, will=20
add by factors to the time spent maintaining all this.

For any extra steps, do them in the call site.

BR, Jarkko