tpm: st33zp24: fix potential buffer overruns caused by bit glitches on the bus

commit 6d24cd186d9fead3722108dec1b1c993354645ff upstream.

Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips.  In all the
driver _recv() functions, we need to use a u32 to unmarshal the
response size, otherwise a bit flip of the 31st bit would cause the
expected variable to go negative, which would then try to read a huge
amount of data.  Also sanity check that the expected amount of data is
large enough for the TPM header.

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>
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>
This commit is contained in:
Jeremy Boone 2018-02-08 12:29:09 -08:00 committed by Greg Kroah-Hartman
parent 47356cfded
commit f9accc380b

View file

@ -485,7 +485,7 @@ static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
size_t count)
{
int size = 0;
int expected;
u32 expected;
if (!chip)
return -EBUSY;
@ -502,7 +502,7 @@ static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
}
expected = be32_to_cpu(*(__be32 *)(buf + 2));
if (expected > count) {
if (expected > count || expected < TPM_HEADER_SIZE) {
size = -EIO;
goto out;
}