Re: [PATCH] tpm: Define TPM2_SPACE_BUFFER_SIZE to replace the use of PAGE_SIZE

On 6/26/20 10:34 AM, Jarkko Sakkinen wrote:

The size of the buffers for storing context's and sessions can vary from arch to arch as PAGE_SIZE can be anything between 4 kB and 256 kB (the maximum for PPC64). Define a fixed buffer size set to 16 kB. This should be enough for most use with three handles (that is how many we allow at the moment).

Reported-by: Stefan Berger stefanb@linux.ibm.com Cc: stable@vger.kernel.org Fixes: 745b361e989a ("tpm: infrastructure for TPM spaces") Signed-off-by: Jarkko Sakkinen jarkko.sakkinen@linux.intel.com

---

drivers/char/tpm/tpm2-space.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index 982d341d8837..9bef646093d1 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -15,6 +15,8 @@ #include <asm/unaligned.h> #include "tpm.h" +#define TPM2_SPACE_BUFFER_SIZE 16384 /* 16 kB */

• enum tpm2_handle_types { TPM2_HT_HMAC_SESSION = 0x02000000, TPM2_HT_POLICY_SESSION = 0x03000000,

@@ -40,11 +42,11 @@ static void tpm2_flush_sessions(struct tpm_chip *chip, struct tpm_space *space) int tpm2_init_space(struct tpm_space *space) {

• space->context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);

• space->context_buf = kzalloc(TPM2_SPACE_BUFFER_SIZE, GFP_KERNEL); if (!space->context_buf) return -ENOMEM;

• space->session_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);

• space->session_buf = kzalloc(TPM2_SPACE_BUFFER_SIZE, GFP_KERNEL); if (space->session_buf == NULL) { kfree(space->context_buf); return -ENOMEM;

@@ -311,8 +313,10 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, sizeof(space->context_tbl)); memcpy(&chip->work_space.session_tbl, &space->session_tbl, sizeof(space->session_tbl));

• memcpy(chip->work_space.context_buf, space->context_buf, PAGE_SIZE);
• memcpy(chip->work_space.session_buf, space->session_buf, PAGE_SIZE);

• memcpy(chip->work_space.context_buf, space->context_buf,

•       TPM2_SPACE_BUFFER_SIZE);
  

• memcpy(chip->work_space.session_buf, space->session_buf,

•       TPM2_SPACE_BUFFER_SIZE);
  

rc = tpm2_load_space(chip); if (rc) { @@ -492,8 +496,8 @@ static int tpm2_save_space(struct tpm_chip *chip) continue; rc = tpm2_save_context(chip, space->context_tbl[i],

• 		       space->context_buf, PAGE_SIZE,
  

• 		       &offset);
  

• 		       space->context_buf,
  

• 		       TPM2_SPACE_BUFFER_SIZE, &offset);
  

  if (rc == -ENOENT) { space->context_tbl[i] = 0; continue;

@@ -509,9 +513,8 @@ static int tpm2_save_space(struct tpm_chip *chip) continue; rc = tpm2_save_context(chip, space->session_tbl[i],

• 		       space->session_buf, PAGE_SIZE,
  

• 		       &offset);
  

• 		       space->session_buf,
  

• 		       TPM2_SPACE_BUFFER_SIZE, &offset);
  

  if (rc == -ENOENT) { /* handle error saving session, just forget it */ space->session_tbl[i] = 0;

@@ -557,8 +560,10 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, sizeof(space->context_tbl)); memcpy(&space->session_tbl, &chip->work_space.session_tbl, sizeof(space->session_tbl));

• memcpy(space->context_buf, chip->work_space.context_buf, PAGE_SIZE);
• memcpy(space->session_buf, chip->work_space.session_buf, PAGE_SIZE);

• memcpy(space->context_buf, chip->work_space.context_buf,

•       TPM2_SPACE_BUFFER_SIZE);
  

• memcpy(space->session_buf, chip->work_space.session_buf,

•       TPM2_SPACE_BUFFER_SIZE);
  

work_space.session_buf and context_buf also need allocation changes, otherwise we read from a smaller buffer here. See comment to other patch about tpm-chip.c .

return 0; out: