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Input: add safety guards to input_set_keycode() 

If we happen to have a garbage in input device's keycode table with values
too big we'll end up doing clear_bit() with offset way outside of our
bitmaps, damaging other objects within an input device or even outside of
it. Let's add sanity checks to the returned old keycodes.

Reported-by: syzbot+c769968809f9359b07aa@syzkaller.appspotmail.com
Reported-by: syzbot+76f3a30e88d256644c78@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20191207212757.GA245964@dtor-ws
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Dmitry Torokhov 2019-12-13 14:56:16 -08:00
parent f729a1b0f8
commit cb222aed03
1 changed files with 16 additions and 10 deletions
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26
drivers/input/input.c
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@ -878,16 +878,18 @@ static int input_default_setkeycode(struct input_dev *dev,
}
}
__clear_bit(*old_keycode, dev->keybit);
__set_bit(ke->keycode, dev->keybit);
for (i = 0; i < dev->keycodemax; i++) {
if (input_fetch_keycode(dev, i) == *old_keycode) {
__set_bit(*old_keycode, dev->keybit);
break; /* Setting the bit twice is useless, so break */
if (*old_keycode <= KEY_MAX) {
__clear_bit(*old_keycode, dev->keybit);
for (i = 0; i < dev->keycodemax; i++) {
if (input_fetch_keycode(dev, i) == *old_keycode) {
__set_bit(*old_keycode, dev->keybit);
/* Setting the bit twice is useless, so break */
break;
}
}
}
__set_bit(ke->keycode, dev->keybit);
return 0;
}
@ -943,9 +945,13 @@ int input_set_keycode(struct input_dev *dev,
* Simulate keyup event if keycode is not present
* in the keymap anymore
*/
if (test_bit(EV_KEY, dev->evbit) &&
!is_event_supported(old_keycode, dev->keybit, KEY_MAX) &&
__test_and_clear_bit(old_keycode, dev->key)) {
if (old_keycode > KEY_MAX) {
dev_warn(dev->dev.parent ?: &dev->dev,
"%s: got too big old keycode %#x\n",
__func__, old_keycode);
} else if (test_bit(EV_KEY, dev->evbit) &&
!is_event_supported(old_keycode, dev->keybit, KEY_MAX) &&
__test_and_clear_bit(old_keycode, dev->key)) {
struct input_value vals[] = {
{ EV_KEY, old_keycode, 0 },
input_value_sync