Commit 7ecd237e authored May 13, 2022 by Stefan Mahnke-Hartmann Committed by Greg Kroah-Hartman Jun 06, 2022

tpm: Fix buffer access in tpm2_get_tpm_pt()



commit e57b2523bd37e6434f4e64c7a685e3715ad21e9a upstream.

Under certain conditions uninitialized memory will be accessed.
As described by TCG Trusted Platform Module Library Specification,
rev. 1.59 (Part 3: Commands), if a TPM2_GetCapability is received,
requesting a capability, the TPM in field upgrade mode may return a
zero length list.
Check the property count in tpm2_get_tpm_pt().

Fixes: 2ab32411 ("tpm: migrate tpm2_get_tpm_pt() to use struct tpm_buf")
Cc: stable@vger.kernel.org
Signed-off-by: Stefan Mahnke-Hartmann <stefan.mahnke-hartmann@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 396d1f51

drivers/char/tpm/tpm2-cmd.c

+10 −1

Original line number	Original line	Diff line number	Diff line
	@@ -706,7 +706,16 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip chip, u32 property_id, u32 value,
	if (!rc) {		if (!rc) {
	out = (struct tpm2_get_cap_out *)		out = (struct tpm2_get_cap_out *)
	&buf.data[TPM_HEADER_SIZE];		&buf.data[TPM_HEADER_SIZE];
			/*
			* To prevent failing boot up of some systems, Infineon TPM2.0
			* returns SUCCESS on TPM2_Startup in field upgrade mode. Also
			* the TPM2_Getcapability command returns a zero length list
			* in field upgrade mode.
			*/
			if (be32_to_cpu(out->property_cnt) > 0)
	*value = be32_to_cpu(out->value);		*value = be32_to_cpu(out->value);
			else
			rc = -ENODATA;
	}		}
	tpm_buf_destroy(&buf);		tpm_buf_destroy(&buf);
	return rc;		return rc;