arno/trezor-firmware
1
0
Fork 0
mirror of https://github.com/trezor/trezor-firmware.git synced 2024-12-22 22:38:08 +00:00
Code Issues Releases Wiki Activity

timer: Fix non-critical integer overflow (#129)

Browse Source 
Every 4294967295 milliseconds (2 ^ 32 - 1), system_millis will overflow.
This means that every 49.71 days, system_millis will reset to zero.
Comparisons like `system_millis < (system_millis + 1)` would fail if the
latter had overflown and the former had not.

This is non-critical because the worst case is that one second could be
skipped or the screen could lock early.

This poses no threat to the exponential backoff used for protection
against brute force.
This commit is contained in:
Saleem Rashid 2016-11-23 19:22:28 +00:00 committed by Pavol Rusnak
parent 15fcda21ce
commit b4eaf7dbaf
5 changed files with 7 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
firmware/layout2.c
View File

@ -84,7 +84,7 @@ void layoutHome(void)
oledRefresh(); oledRefresh();
// Reset lock screen timeout // Reset lock screen timeout
system_millis_lock = system_millis + SCREEN_TIMEOUT_MILLIS; system_millis_lock_start = system_millis;
} }
const char *str_amount(uint64_t amnt, const char *abbr, char *buf, int len) const char *str_amount(uint64_t amnt, const char *abbr, char *buf, int len)

2
firmware/trezor.c
View File

@ -79,7 +79,7 @@ void check_lock_screen(void)
// if homescreen is shown for longer than 10 minutes, lock too // if homescreen is shown for longer than 10 minutes, lock too
if (layoutLast == layoutHome) { if (layoutLast == layoutHome) {
if (system_millis >= system_millis_lock) { if ((system_millis - system_millis_lock_start) >= 60000) {
// lock the screen // lock the screen
session_clear(true); session_clear(true);
layoutScreensaver(); layoutScreensaver();

5
firmware/usb.c
View File

@ -429,8 +429,9 @@ char usbTiny(char set)
void usbSleep(uint32_t millis) void usbSleep(uint32_t millis)
{ {
uint32_t end = system_millis + millis; uint32_t start = system_millis;
while (end > system_millis) {
while ((system_millis - start) < millis) {
usbd_poll(usbd_dev); usbd_poll(usbd_dev);
} }
} }

2
timer.c
View File

@ -27,7 +27,7 @@
volatile uint32_t system_millis; volatile uint32_t system_millis;
/* Screen timeout */ /* Screen timeout */
uint32_t system_millis_lock; uint32_t system_millis_lock_start;
/* /*
* Initialise the Cortex-M3 SysTick timer * Initialise the Cortex-M3 SysTick timer

4
timer.h
View File

@ -24,9 +24,7 @@
extern volatile uint32_t system_millis; extern volatile uint32_t system_millis;
/* Screen timeout */ /* Screen timeout */
extern uint32_t system_millis_lock; extern uint32_t system_millis_lock_start;
#define SCREEN_TIMEOUT_MILLIS (1000 * 60 * 10) /* 10 minutes */
void timer_init(void); void timer_init(void);