On 01/30/2017 02:50 AM, Jarkko Sakkinen wrote: > On Sun, Jan 29, 2017 at 10:48:39PM +0530, Nayna wrote: >> >> >> On 01/29/2017 08:10 PM, Jarkko Sakkinen wrote: >>> 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 <[email protected]> >>>> Signed-off-by: Nayna Jain <[email protected]> >>> >>> 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. >> >> Sure will update. >> >>> >>>> int rc; >>>> - int i; >>>> + int i = 0; >>> >>> Why do you need to initialize it? >> >> Because in out: count is replaced with i. >> And it is replaced because now for loop can break even before reaching >> count, because of new buffer checks. >>> >>>> >>>> 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? >> >> Isn't this check need to be done in tpm_transmit_cmd for all responses ? >> Though, it seems it is not done there as well. >> >> And to understand what do we expect max buffer length. PAGE_SIZE or >> TPM_BUFSIZE ? > > Oops. You are correct it is done there: > > if (len != be32_to_cpu(header->length)) > return -EFAULT; > > So need to do this.
To be sure, means nothing need to be done in this. Right ? And guess this was the only thing you meant by broken for this patch. I will do other two smaller changes as I send the whole new patchset. Thanks & Regards, - Nayna > > /Jarkko > > /Jarkko > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ tpmdd-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/tpmdd-devel
