Messages in this thread | | | Date | Sun, 29 Jan 2017 16:40:37 +0200 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH] tpm: add buffer access validation in tpm2_get_pcr_allocation() |
| |
On Fri, Jan 27, 2017 at 10:25:49AM -0500, Nayna Jain wrote: > This patch add validation in tpm2_get_pcr_allocation to avoid > access beyond response buffer length. > > Suggested-by: Stefan Berger <stefanb@linux.vnet.ibm.com> > Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
This validation looks broken to me.
> --- > drivers/char/tpm/tpm2-cmd.c | 28 +++++++++++++++++++++++----- > 1 file changed, 23 insertions(+), 5 deletions(-) > > diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c > index 4aad84c..02c1ea7 100644 > --- a/drivers/char/tpm/tpm2-cmd.c > +++ b/drivers/char/tpm/tpm2-cmd.c > @@ -1008,9 +1008,13 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip) > struct tpm2_pcr_selection pcr_selection; > struct tpm_buf buf; > void *marker; > - unsigned int count = 0; > + void *end; > + void *pcr_select_offset; > + unsigned int count; > + u32 sizeof_pcr_selection; > + u32 resp_len;
Very cosmetic but we almos almost universally use the acronym 'rsp' in the TPM driver.
> int rc; > - int i; > + int i = 0;
Why do you need to initialize it?
> > rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY); > if (rc) > @@ -1034,15 +1038,29 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip) > } > > marker = &buf.data[TPM_HEADER_SIZE + 9]; > + > + resp_len = be32_to_cpup((__be32 *)&buf.data[2]); > + end = &buf.data[resp_len];
What if the response contains larger length than the buffer size?
> + > for (i = 0; i < count; i++) { > + pcr_select_offset = marker + > + offsetof(struct tpm2_pcr_selection, size_of_select); > + if (pcr_select_offset >= end) { > + rc = -EFAULT; > + break; > + } > + > memcpy(&pcr_selection, marker, sizeof(pcr_selection)); > chip->active_banks[i] = be16_to_cpu(pcr_selection.hash_alg); > - marker = marker + sizeof(struct tpm2_pcr_selection); > + sizeof_pcr_selection = sizeof(pcr_selection.hash_alg) + > + sizeof(pcr_selection.size_of_select) + > + sizeof(u8) * pcr_selection.size_of_select;
Remove "sizeof(u8) * ".
> + marker = marker + sizeof_pcr_selection; > } > > out: > - if (count < ARRAY_SIZE(chip->active_banks)) > - chip->active_banks[count] = TPM2_ALG_ERROR; > + if (i < ARRAY_SIZE(chip->active_banks)) > + chip->active_banks[i] = TPM2_ALG_ERROR; > > tpm_buf_destroy(&buf); > > -- > 2.5.0 >
I'm sorry but this commit is changing too much. You need to redo the whole commit and resend the patch set with these fixes. You can keep Reviewed-by and Tested-by in 1/2 but have to remove them from 2/2.
/Jarkko
| |