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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: Jia Zhang <zhang.jia@linux.alibaba.com>
Reviewd-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Jia Zhang 2019-01-11 16:59:32 +08:00 committed by Jarkko Sakkinen
parent 442601e87a
commit bb3b6b0fc5
1 changed files with 14 additions and 23 deletions
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37
drivers/char/tpm/eventlog/tpm1.c
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@ -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;
@ -83,38 +83,29 @@ 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);
}
}
if (((converted_event_type == 0) && (converted_event_size == 0))
|| ((addr + sizeof(struct tcpa_event) + converted_event_size)
>= limit))
return NULL;
/* now check if current entry is valid */
if ((addr + sizeof(struct tcpa_event)) >= limit)
return NULL;
if (i++ == *pos)
break;
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;
addr += (sizeof(struct tcpa_event) + converted_event_size);
} while (1);
return addr;
}