2017-03-11 00:46:58

by Jerry Snitselaar

Subject: [PATCH] tpm_crb: check for bad response size

Make sure size of response buffer is at least 6 bytes, or
we will underflow and pass large size_t to memcpy_fromio().
This was encountered while testing earlier version of
locality patchset.

Fixes: 30fc8d138e912 ("tpm: TPM 2.0 CRB Interface")
Signed-off-by: Jerry Snitselaar <[email protected]>
---
drivers/char/tpm/tpm_crb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 89dc8a176ff1..cda4f312d1c9 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -236,7 +236,7 @@ static int crb_recv(struct tpm_chip *chip, u8 *buf, size_t count)

memcpy_fromio(buf, priv->rsp, 6);
expected = be32_to_cpup((__be32 *) &buf[2]);
- if (expected > count)
+ if (expected > count || expected < 6)
return -EIO;

memcpy_fromio(&buf[6], &priv->rsp[6], expected - 6);
--
2.11.0.258.ge05806da9

2017-03-11 08:48:30

by Jarkko Sakkinen

Subject: Re: [PATCH] tpm_crb: check for bad response size

On Fri, Mar 10, 2017 at 05:46:04PM -0700, Jerry Snitselaar wrote:
> Make sure size of response buffer is at least 6 bytes, or
> we will underflow and pass large size_t to memcpy_fromio().
> This was encountered while testing earlier version of
> locality patchset.
>
> Fixes: 30fc8d138e912 ("tpm: TPM 2.0 CRB Interface")
> Signed-off-by: Jerry Snitselaar <[email protected]>

Reviewed-by: Jarkko Sakkinen <[email protected]>

/Jarkko

> ---
> drivers/char/tpm/tpm_crb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index 89dc8a176ff1..cda4f312d1c9 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -236,7 +236,7 @@ static int crb_recv(struct tpm_chip *chip, u8 *buf, size_t count)
>
> memcpy_fromio(buf, priv->rsp, 6);
> expected = be32_to_cpup((__be32 *) &buf[2]);
> - if (expected > count)
> + if (expected > count || expected < 6)
> return -EIO;
>
> memcpy_fromio(&buf[6], &priv->rsp[6], expected - 6);
> --
> 2.11.0.258.ge05806da9
>