linux-kernel - Re: [PATCH] tpm: infineon: add bounds check in tpm_inf

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Message-ID: <aOETD4GrSrQGkIAx@kernel.org>
Date: Sat, 4 Oct 2025 15:29:03 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Shahriyar Jalayeri <shahriyar@...teo.de>
Cc: peterhuewe@....de, jgg@...pe.ca, linux-integrity@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: infineon: add bounds check in tpm_inf_recv

On Fri, Oct 03, 2025 at 09:25:47AM +0000, Shahriyar Jalayeri wrote:
> Ensure tpm_inf_recv() does not overflow the provided buffer when
> the TPM reports more data than the caller expects.
> 
> Signed-off-by: Shahriyar Jalayeri <shahriyar@...teo.de>

missing:

Fixes: ebb81fdb3dd0 ("[PATCH] tpm: Support for Infineon TPM")

> ---
>  drivers/char/tpm/tpm_infineon.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/char/tpm/tpm_infineon.c b/drivers/char/tpm/tpm_infineon.c
> index 7638b65b8..eb6dd55ff 100644
> --- a/drivers/char/tpm/tpm_infineon.c
> +++ b/drivers/char/tpm/tpm_infineon.c
> @@ -250,6 +250,12 @@ static int tpm_inf_recv(struct tpm_chip *chip, u8 * buf, size_t count)
>  	number_of_wtx = 0;
>  
>  recv_begin:
> +	if (count < 4) {
> +		dev_err(&chip->dev,
> +			"count less than the header size!\n");
> +		return -EIO;
> +	}

Please remove dev_err() 

> +
>  	/* start receiving header */
>  	for (i = 0; i < 4; i++) {
>  		ret = wait(chip, STAT_RDA);
> @@ -268,6 +274,12 @@ static int tpm_inf_recv(struct tpm_chip *chip, u8 * buf, size_t count)
>  		/* size of the data received */
>  		size = ((buf[2] << 8) | buf[3]);
>  
> +		if (size > count) {
> +			dev_err(&chip->dev,
> +				"Buffer too small for incoming data!\n");
> +			return -EIO;
> +		}


Ditto
>
>  		for (i = 0; i < size; i++) {
>  			wait(chip, STAT_RDA);
>  			buf[i] = tpm_data_in(RDFIFO);
> -- 
> 2.43.0

BR, Jarkko