4.4-stable review patch. If anyone has any objections, please let me know.
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From: Jeremy Boone jeremy.boone@nccgroup.trust
commit 6bb320ca4a4a7b5b3db8c8d7250cc40002046878 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 Tested-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.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
--- drivers/char/tpm/tpm_tis.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/char/tpm/tpm_tis.c +++ b/drivers/char/tpm/tpm_tis.c @@ -283,7 +283,8 @@ static int recv_data(struct tpm_chip *ch static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count) { int size = 0; - int expected, status; + int status; + u32 expected;
if (count < TPM_HEADER_SIZE) { size = -EIO; @@ -298,7 +299,7 @@ static int tpm_tis_recv(struct tpm_chip }
expected = be32_to_cpu(*(__be32 *) (buf + 2)); - if (expected > count) { + if (expected > count || expected < TPM_HEADER_SIZE) { size = -EIO; goto out; }