fdo-mirrors/libevdev
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/libevdev/libevdev.git synced 2025-12-20 19:40:06 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

Drop invalid ABS_MT_TRACKING_ID changes

Browse source 
Follow-up to
commit 41334b5b40
Author: Peter Hutterer <peter.hutterer@who-t.net>
Date:   Thu Mar 6 11:54:00 2014 +1000

    If the tracking ID changes during SYN_DROPPED, terminate the touch first

In normal mode, we may get double tracking ID events in the same slot, but
only if we either have a user-generated event sequence (uinput) or a malicious
device that tries to send data on a slot > dev->num_slots.
Since the client is unlikely to be able to handle these events, discard the
ABS_MT_TRACKING_ID completely. This is a bug somewhere in the stack, so
complain and hobble on along.

Note: the kernel doesn't allow that, but we cap to num_slots anyway, see
66fee1bec4.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
This commit is contained in:
Peter Hutterer 2014-04-01 17:01:39 +10:00
parent 27df93737e
commit 6cbf971b39
2 changed files with 196 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

43
libevdev/libevdev.c
View file

@ -36,6 +36,12 @@
#define MAXEVENTS 64
enum event_filter_status {
EVENT_FILTER_NONE, /**< Event untouched by filters */
EVENT_FILTER_MODIFIED, /**< Event was modified */
EVENT_FILTER_DISCARD, /**< Discard current event */
};
static int sync_mt_state(struct libevdev *dev, int create_events);
static inline int*
@ -880,10 +886,11 @@ read_more_events(struct libevdev *dev)
/**
* Sanitize/modify events where needed.
* @return 0 if untouched, 1 if modified.
*/
static inline int
sanitize_event(const struct libevdev *dev, struct input_event *ev)
static inline enum event_filter_status
sanitize_event(const struct libevdev *dev,
struct input_event *ev,
enum SyncState sync_state)
{
if (unlikely(dev->num_slots > -1 &&
libevdev_event_is_code(ev, EV_ABS, ABS_MT_SLOT) &&
@ -892,16 +899,32 @@ sanitize_event(const struct libevdev *dev, struct input_event *ev)
"Capping to announced max slot number %d.\n",
dev->name, ev->value, dev->num_slots - 1);
ev->value = dev->num_slots - 1;
return 1;
return EVENT_FILTER_MODIFIED;
/* Drop any invalid tracking IDs, they are only supposed to go from
N to -1 or from -1 to N. Never from -1 to -1, or N to M. Very
unlikely to ever happen from a real device.
*/
} else if (unlikely(sync_state == SYNC_NONE &&
dev->num_slots > -1 &&
libevdev_event_is_code(ev, EV_ABS, ABS_MT_TRACKING_ID) &&
((ev->value == -1 &&
*slot_value(dev, dev->current_slot, ABS_MT_TRACKING_ID) == -1) ||
(ev->value != -1 &&
*slot_value(dev, dev->current_slot, ABS_MT_TRACKING_ID) != -1)))) {
log_bug("Device \"%s\" received a double tracking ID %d in slot %d.\n",
dev->name, ev->value, dev->current_slot);
return EVENT_FILTER_DISCARD;
}
return 0;
return EVENT_FILTER_NONE;
}
LIBEVDEV_EXPORT int
libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_event *ev)
{
int rc = LIBEVDEV_READ_STATUS_SUCCESS;
enum event_filter_status filter_status;
if (!dev->initialized) {
log_bug("device not initialized. call libevdev_set_fd() first\n");
@ -934,7 +957,7 @@ libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_event
of the device too */
while (queue_shift(dev, &e) == 0) {
dev->queue_nsync--;
sanitize_event(dev, &e);
if (sanitize_event(dev, &e, dev->sync_state) != EVENT_FILTER_DISCARD)
update_state(dev, &e);
}
@ -965,11 +988,13 @@ libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_event
if (queue_shift(dev, ev) != 0)
return -EAGAIN;
sanitize_event(dev, ev);
filter_status = sanitize_event(dev, ev, dev->sync_state);
if (filter_status != EVENT_FILTER_DISCARD)
update_state(dev, ev);
/* if we disabled a code, get the next event instead */
} while(!libevdev_has_event_code(dev, ev->type, ev->code));
} while(filter_status == EVENT_FILTER_DISCARD ||
!libevdev_has_event_code(dev, ev->type, ev->code));
rc = LIBEVDEV_READ_STATUS_SUCCESS;
if (ev->type == EV_SYN && ev->code == SYN_DROPPED) {
@ -1163,7 +1188,7 @@ libevdev_set_event_value(struct libevdev *dev, unsigned int type, unsigned int c
e.code = code;
e.value = value;
if (sanitize_event(dev, &e))
if (sanitize_event(dev, &e, SYNC_NONE) != EVENT_FILTER_NONE)
return -1;
switch(type) {

160
test/test-libevdev-events.c
View file

@ -1424,6 +1424,164 @@ START_TEST(test_mt_slot_ranges_invalid)
}
END_TEST
START_TEST(test_mt_tracking_id_discard)
{
struct uinput_device* uidev;
struct libevdev *dev;
int rc;
struct input_event ev;
struct input_absinfo abs[6];
memset(abs, 0, sizeof(abs));
abs[0].value = ABS_X;
abs[0].maximum = 1000;
abs[1].value = ABS_MT_POSITION_X;
abs[1].maximum = 1000;
abs[2].value = ABS_Y;
abs[2].maximum = 1000;
abs[3].value = ABS_MT_POSITION_Y;
abs[3].maximum = 1000;
abs[4].value = ABS_MT_SLOT;
abs[4].maximum = 10;
abs[5].value = ABS_MT_TRACKING_ID;
abs[5].maximum = 500;
rc = test_create_abs_device(&uidev, &dev,
6, abs,
EV_SYN, SYN_REPORT,
-1);
uinput_device_event(uidev, EV_ABS, ABS_MT_SLOT, 1);
uinput_device_event(uidev, EV_ABS, ABS_MT_TRACKING_ID, 1);
uinput_device_event(uidev, EV_SYN, SYN_REPORT, 0);
/* second tracking ID on same slot */
uinput_device_event(uidev, EV_ABS, ABS_MT_TRACKING_ID, 2);
uinput_device_event(uidev, EV_SYN, SYN_REPORT, 0);
libevdev_set_log_function(test_logfunc_ignore_error, NULL);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_ABS);
ck_assert_int_eq(ev.code, ABS_MT_SLOT);
ck_assert_int_eq(ev.value, 1);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_ABS);
ck_assert_int_eq(ev.code, ABS_MT_TRACKING_ID);
ck_assert_int_eq(ev.value, 1);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_SYN);
ck_assert_int_eq(ev.code, SYN_REPORT);
ck_assert_int_eq(ev.value, 0);
/* expect tracking ID discarded */
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_SYN);
ck_assert_int_eq(ev.code, SYN_REPORT);
ck_assert_int_eq(ev.value, 0);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, -EAGAIN);
libevdev_set_log_function(test_logfunc_abort_on_error, NULL);
uinput_device_free(uidev);
libevdev_free(dev);
}
END_TEST
START_TEST(test_mt_tracking_id_discard_neg_1)
{
struct uinput_device* uidev;
struct libevdev *dev;
int rc;
struct input_event ev;
struct input_absinfo abs[6];
int pipefd[2];
struct input_event events[] = {
{ .type = EV_ABS, .code = ABS_MT_TRACKING_ID, .value = -1 },
{ .type = EV_SYN, .code = SYN_REPORT, .value = 0 },
};
rc = pipe2(pipefd, O_NONBLOCK);
ck_assert_int_eq(rc, 0);
memset(abs, 0, sizeof(abs));
abs[0].value = ABS_X;
abs[0].maximum = 1000;
abs[1].value = ABS_MT_POSITION_X;
abs[1].maximum = 1000;
abs[2].value = ABS_Y;
abs[2].maximum = 1000;
abs[3].value = ABS_MT_POSITION_Y;
abs[3].maximum = 1000;
abs[4].value = ABS_MT_SLOT;
abs[4].maximum = 10;
abs[5].value = ABS_MT_TRACKING_ID;
abs[5].maximum = 500;
rc = test_create_abs_device(&uidev, &dev,
6, abs,
EV_SYN, SYN_REPORT,
-1);
uinput_device_event(uidev, EV_ABS, ABS_MT_SLOT, 1);
uinput_device_event(uidev, EV_ABS, ABS_MT_TRACKING_ID, 1);
uinput_device_event(uidev, EV_SYN, SYN_REPORT, 0);
while (libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev) != -EAGAIN)
;
libevdev_set_log_function(test_logfunc_ignore_error, NULL);
/* two -1 tracking ids, need to use the pipe here, the kernel will
filter it otherwise */
libevdev_change_fd(dev, pipefd[0]);
rc = write(pipefd[1], events, sizeof(events));
ck_assert_int_eq(rc, sizeof(events));
rc = write(pipefd[1], events, sizeof(events));
ck_assert_int_eq(rc, sizeof(events));
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_ABS);
ck_assert_int_eq(ev.code, ABS_MT_TRACKING_ID);
ck_assert_int_eq(ev.value, -1);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_SYN);
ck_assert_int_eq(ev.code, SYN_REPORT);
ck_assert_int_eq(ev.value, 0);
/* expect second tracking ID discarded */
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, LIBEVDEV_READ_STATUS_SUCCESS);
ck_assert_int_eq(ev.type, EV_SYN);
ck_assert_int_eq(ev.code, SYN_REPORT);
ck_assert_int_eq(ev.value, 0);
rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
ck_assert_int_eq(rc, -EAGAIN);
libevdev_set_log_function(test_logfunc_abort_on_error, NULL);
uinput_device_free(uidev);
libevdev_free(dev);
}
END_TEST
START_TEST(test_ev_rep_values)
{
struct uinput_device* uidev;
@ -1719,6 +1877,8 @@ libevdev_events(void)
tcase_add_test(tc, test_mt_event_values);
tcase_add_test(tc, test_mt_event_values_invalid);
tcase_add_test(tc, test_mt_slot_ranges_invalid);
tcase_add_test(tc, test_mt_tracking_id_discard);
tcase_add_test(tc, test_mt_tracking_id_discard_neg_1);
tcase_add_test(tc, test_ev_rep_values);
suite_add_tcase(s, tc);