On Mon, Apr 1, 2019 at 11:52 AM James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > > On Mon, 2019-04-01 at 11:32 -0700, Kees Cook wrote: > [...] > > --- a/drivers/char/tpm/tpm1-cmd.c > > +++ b/drivers/char/tpm/tpm1-cmd.c > > @@ -510,7 +510,7 @@ struct tpm1_get_random_out { > > * > > * Return: > > * * number of bytes read > > - * * -errno or a TPM return code otherwise > > + * * -errno (positive TPM return codes are masked to -EIO) > > */ > > int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max) > > { > > @@ -524,7 +524,7 @@ int tpm1_get_random(struct tpm_chip *chip, u8 > > *dest, size_t max) > > > > rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, > > TPM_ORD_GET_RANDOM); > > if (rc) > > - return rc; > > + goto fail; > > > > do { > > tpm_buf_append_u32(&buf, num_bytes); > > @@ -559,7 +559,10 @@ int tpm1_get_random(struct tpm_chip *chip, u8 > > *dest, size_t max) > > rc = total ? (int)total : -EIO; > > out: > > tpm_buf_destroy(&buf); > > - return rc; > > You can't remove this otherwise the only return will ever be a failure. > > I think what you're trying to catch is tpm_transmit_cmd returning a > positive failure, So you need to check the output of tpm_transmit_cmd > as well and goto failure leaving the above return in place. eek, yes. I double-checked this in tpm2, but tpm1 is different... -- Kees Cook