On Tue, Oct 07, 2025 at 09:07:39AM +0000, Shahriyar Jalayeri wrote:
> Add two buffer size validations to prevent buffer overflows in
> tpm_inf_recv():
>
> 1. Validate that the provided buffer can hold at least the 4-byte header
> before attempting to read it.
> 2. Validate that the buffer is large enough to hold the data size reported
> by the TPM before reading the payload.
>
> Without these checks, a malicious or malfunctioning TPM could cause buffer
> overflows by reporting data sizes larger than the provided buffer, leading
> to memory corruption.
>
> Fixes: ebb81fdb3dd0 ("[PATCH] tpm: Support for Infineon TPM")
> Signed-off-by: Shahriyar Jalayeri <[email protected]>
> ---
> drivers/char/tpm/tpm_infineon.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm_infineon.c b/drivers/char/tpm/tpm_infineon.c
> index 7638b65b8..8b90a8191 100644
> --- a/drivers/char/tpm/tpm_infineon.c
> +++ b/drivers/char/tpm/tpm_infineon.c
> @@ -250,6 +250,11 @@ static int tpm_inf_recv(struct tpm_chip *chip, u8 * buf,
> size_t count)
> number_of_wtx = 0;
>
> recv_begin:
> + /* expect at least 1-byte VL header, 1-byte ctrl-tag, 2-byte data size */
> + if (count < 4) {
> + return -EIO;
> + }
> +
> /* start receiving header */
> for (i = 0; i < 4; i++) {
> ret = wait(chip, STAT_RDA);
> @@ -268,6 +273,10 @@ 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 + 6 > count) {
> + return -EIO;
> + }
> +
> for (i = 0; i < size; i++) {
> wait(chip, STAT_RDA);
> buf[i] = tpm_data_in(RDFIFO);
> --
> 2.43.0
>
Nitpick: we don't use curly braces for one line statements.
AFAIK scripts/checkpatch.pl complains about this. Other than that
I don't see any issues.
BR, Jarkko
