Commit bb3b6b0f authored by Jia Zhang's avatar Jia Zhang Committed by Jarkko Sakkinen
Browse files

tpm: Simplify the measurements loop 



The responsibility of tpm1_bios_measurements_start() is to walk over the
first *pos measurements, ensuring the skipped and to-be-read
measurements are not out-of-boundary.

This commit simplifies the loop by employing a do-while loop with
the necessary sanity check.

Signed-off-by: default avatarJia Zhang <zhang.jia@linux.alibaba.com>
Reviewd-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
parent 442601e8

drivers/char/tpm/eventlog/tpm1.c

+14 −23
Original line number Diff line number Diff line
@@ -74,7 +74,7 @@ static const char* tcpa_pc_event_id_strings[] = { 
/* returns pointer to start of pos. entry of tcg log */

static void *tpm1_bios_measurements_start(struct seq_file *m, loff_t *pos)

{

	loff_t i;

	loff_t i = 0;

	struct tpm_chip *chip = m->private;

	struct tpm_bios_log *log = &chip->log;

	void *addr = log->bios_event_log;
@@ -83,39 +83,30 @@ static void *tpm1_bios_measurements_start(struct seq_file *m, loff_t *pos) 
	u32 converted_event_size;

	u32 converted_event_type;





	/* read over *pos measurements */

	for (i = 0; i < *pos; i++) {

	do {

		event = addr;



		/* check if current entry is valid */

		if (addr + sizeof(struct tcpa_event) >= limit)

			return NULL;



		converted_event_size =

		    do_endian_conversion(event->event_size);

		converted_event_type =

		    do_endian_conversion(event->event_type);



		if ((addr + sizeof(struct tcpa_event)) < limit) {

			if ((converted_event_type == 0) &&

			    (converted_event_size == 0))

				return NULL;

			addr += (sizeof(struct tcpa_event) +

				 converted_event_size);

		}

	}



	/* now check if current entry is valid */

	if ((addr + sizeof(struct tcpa_event)) >= limit)

		return NULL;



	event = addr;



	converted_event_size = do_endian_conversion(event->event_size);

	converted_event_type = do_endian_conversion(event->event_type);



		if (((converted_event_type == 0) && (converted_event_size == 0))

		    || ((addr + sizeof(struct tcpa_event) + converted_event_size)

			>= limit))

			return NULL;



		if (i++ == *pos)

			break;



		addr += (sizeof(struct tcpa_event) + converted_event_size);

	} while (1);



	return addr;

}

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