3.2.102-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Jeremy Boone <[email protected]> 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 <[email protected]> Signed-off-by: James Bottomley <[email protected]> Tested-by: Jarkko Sakkinen <[email protected]> Reviewed-by: Jarkko Sakkinen <[email protected]> Signed-off-by: Jarkko Sakkinen <[email protected]> Signed-off-by: James Morris <[email protected]> [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings <[email protected]> --- 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 @@ -253,7 +253,8 @@ 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; @@ -268,7 +269,7 @@ 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; }
