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Subject[PATCH 4.4 01/97] tpm: fix potential buffer overruns caused by bit glitches on the bus
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeremy Boone <jeremy.boone@nccgroup.trust>

commit 3be23274755ee85771270a23af7691dc9b3a95db upstream.

Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips. If a bit does
flip it could cause an overrun if it's in one of the size parameters,
so sanity check that we're not overrunning the provided buffer when
doing a memcpy().

Signed-off-by: Jeremy Boone <jeremy.boone@nccgroup.trust>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/char/tpm/tpm-interface.c | 5 +++++
drivers/char/tpm/tpm2-cmd.c | 6 ++++++
2 files changed, 11 insertions(+)

--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1040,6 +1040,11 @@ int tpm_get_random(u32 chip_num, u8 *out
break;

recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len);
+ if (recd > num_bytes) {
+ total = -EFAULT;
+ break;
+ }
+
memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd);

dest += recd;
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -622,6 +622,11 @@ static int tpm2_unseal_cmd(struct tpm_ch
if (!rc) {
data_len = be16_to_cpup(
(__be16 *) &buf.data[TPM_HEADER_SIZE + 4]);
+ if (data_len < MIN_KEY_SIZE || data_len > MAX_KEY_SIZE + 1) {
+ rc = -EFAULT;
+ goto out;
+ }
+
data = &buf.data[TPM_HEADER_SIZE + 6];

memcpy(payload->key, data, data_len - 1);
@@ -629,6 +634,7 @@ static int tpm2_unseal_cmd(struct tpm_ch
payload->migratable = data[data_len - 1];
}

+out:
tpm_buf_destroy(&buf);
return rc;
}

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