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.
Current logic is complicated a bit. Just employ a do-while loop
with necessary sanity check, and then get the goal.
Signed-off-by: Jia Zhang <zhang.jia@xxxxxxxxxxxxxxxxx>
---
drivers/char/tpm/eventlog/tpm1.c | 37 ++++++++++++++-----------------------
1 file changed, 14 insertions(+), 23 deletions(-)
diff --git a/drivers/char/tpm/eventlog/tpm1.c b/drivers/char/tpm/eventlog/tpm1.c
index 58c8478..4cf8303 100644
--- a/drivers/char/tpm/eventlog/tpm1.c
+++ b/drivers/char/tpm/eventlog/tpm1.c
@@ -74,7 +74,7 @@
/* 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);
- }
- }
-
- /* now check if current entry is valid */
- if ((addr + sizeof(struct tcpa_event)) >= limit)
- return NULL;
-
- event = addr;
+ if (((converted_event_type == 0) && (converted_event_size == 0))
+ || ((addr + sizeof(struct tcpa_event) + converted_event_size)
+ >= limit))
+ return NULL;
- converted_event_size = do_endian_conversion(event->event_size);
- converted_event_type = do_endian_conversion(event->event_type);
+ if (i++ == *pos)
+ break;
- 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;
}
--
1.8.3.1
