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Commit c6d2e202 authored Sep 03, 2018 by Jarkko Sakkinen Committed by Greg Kroah-Hartman Nov 13, 2018

tpm: fix response size validation in tpm_get_random()



commit 84b59f6487d82d3ab4247a099aba66d4d17e8b08 upstream.

When checking whether the response is large enough to be able to contain
the received random bytes in tpm_get_random() and tpm2_get_random(),
they fail to take account the header size, which should be added to the
minimum size. This commit fixes this issue.

Cc: stable@vger.kernel.org
Fixes: c659af78 ("tpm: Check size of response before accessing data")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e6d2f788

drivers/char/tpm/tpm-interface.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1322,7 +1322,8 @@ int tpm_get_random(struct tpm_chip chip, u8 out, size_t max)
		}

		rlength = be32_to_cpu(tpm_cmd.header.out.length);
		if (rlength < offsetof(struct tpm_getrandom_out, rng_data) +
		if (rlength < TPM_HEADER_SIZE +
		offsetof(struct tpm_getrandom_out, rng_data) +
		recd) {
		total = -EFAULT;
		break;

drivers/char/tpm/tpm2-cmd.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -329,7 +329,9 @@ int tpm2_get_random(struct tpm_chip chip, u8 dest, size_t max)
		&buf.data[TPM_HEADER_SIZE];
		recd = min_t(u32, be16_to_cpu(out->size), num_bytes);
		if (tpm_buf_length(&buf) <
		offsetof(struct tpm2_get_random_out, buffer) + recd) {
		TPM_HEADER_SIZE +
		offsetof(struct tpm2_get_random_out, buffer) +
		recd) {
		err = -EFAULT;
		goto out;
		}