tpm: fix potential buffer overruns caused by bit glitches on the bus

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>

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index d0ac2d5..830d7e3 100644 (file)
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -1078,6 +1078,11 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
                        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;

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 17896d6..a5780eb 100644 (file)
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -668,6 +668,11 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
        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);
@@ -675,6 +680,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
                payload->migratable = data[data_len - 1];
        }
 
+out:
        tpm_buf_destroy(&buf);
        return rc;
 }