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


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