Commit 6d24cd18 authored by Jeremy Boone's avatar Jeremy Boone Committed by James Morris

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

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: default avatarJeremy Boone <jeremy.boone@nccgroup.trust>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarJames Morris <james.morris@microsoft.com>
parent 9b8cb28d
......@@ -457,7 +457,7 @@ 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;
......@@ -474,7 +474,7 @@ 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;
}
......
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