From 53a62800efb2f0ebc1972cab242461ae8c57bfd4 Mon Sep 17 00:00:00 2001 From: Sean Young Date: Thu, 12 Apr 2018 16:28:39 -0400 Subject: [PATCH] media: rc: mce_kbd decoder: fix race condition The MCE keyboard sends both key down and key up events. We have a timeout handler mce_kbd_rx_timeout() in case the keyup event is never received; however, this may race with new key down events from occurring. The race is that key down scancode arrives and key down events are generated. The timeout handler races this and generates key up events straight afterwards. Since the keyboard generates scancodes every 100ms, most likely the keys will be repeated 100ms later, and now we have new key down events and the user sees duplicate key presses. Reported-by: Matthias Reichl Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab --- drivers/media/rc/ir-mce_kbd-decoder.c | 23 ++++++++++++++++------- drivers/media/rc/rc-core-priv.h | 2 ++ 2 files changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/media/rc/ir-mce_kbd-decoder.c b/drivers/media/rc/ir-mce_kbd-decoder.c index 2fc78710a724..9574c3dd90f2 100644 --- a/drivers/media/rc/ir-mce_kbd-decoder.c +++ b/drivers/media/rc/ir-mce_kbd-decoder.c @@ -119,19 +119,25 @@ static void mce_kbd_rx_timeout(struct timer_list *t) { struct ir_raw_event_ctrl *raw = from_timer(raw, t, mce_kbd.rx_timeout); unsigned char maskcode; + unsigned long flags; int i; dev_dbg(&raw->dev->dev, "timer callback clearing all keys\n"); - for (i = 0; i < 7; i++) { - maskcode = kbd_keycodes[MCIR2_MASK_KEYS_START + i]; - input_report_key(raw->mce_kbd.idev, maskcode, 0); - } + spin_lock_irqsave(&raw->mce_kbd.keylock, flags); - for (i = 0; i < MCIR2_MASK_KEYS_START; i++) - input_report_key(raw->mce_kbd.idev, kbd_keycodes[i], 0); + if (time_is_before_eq_jiffies(raw->mce_kbd.rx_timeout.expires)) { + for (i = 0; i < 7; i++) { + maskcode = kbd_keycodes[MCIR2_MASK_KEYS_START + i]; + input_report_key(raw->mce_kbd.idev, maskcode, 0); + } - input_sync(raw->mce_kbd.idev); + for (i = 0; i < MCIR2_MASK_KEYS_START; i++) + input_report_key(raw->mce_kbd.idev, kbd_keycodes[i], 0); + + input_sync(raw->mce_kbd.idev); + } + spin_unlock_irqrestore(&raw->mce_kbd.keylock, flags); } static enum mce_kbd_mode mce_kbd_mode(struct mce_kbd_dec *data) @@ -327,6 +333,7 @@ again: scancode = data->body & 0xffffff; dev_dbg(&dev->dev, "keyboard data 0x%08x\n", data->body); + spin_lock(&data->keylock); if (scancode) { delay = nsecs_to_jiffies(dev->timeout) + msecs_to_jiffies(100); @@ -336,6 +343,7 @@ again: } /* Pass data to keyboard buffer parser */ ir_mce_kbd_process_keyboard_data(dev, scancode); + spin_unlock(&data->keylock); lsc.rc_proto = RC_PROTO_MCIR2_KBD; break; case MCIR2_MOUSE_NBITS: @@ -400,6 +408,7 @@ static int ir_mce_kbd_register(struct rc_dev *dev) set_bit(MSC_SCAN, idev->mscbit); timer_setup(&mce_kbd->rx_timeout, mce_kbd_rx_timeout, 0); + spin_lock_init(&mce_kbd->keylock); input_set_drvdata(idev, mce_kbd); diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h index f78551344eca..07ba77fe6a3b 100644 --- a/drivers/media/rc/rc-core-priv.h +++ b/drivers/media/rc/rc-core-priv.h @@ -105,6 +105,8 @@ struct ir_raw_event_ctrl { } sharp; struct mce_kbd_dec { struct input_dev *idev; + /* locks key up timer */ + spinlock_t keylock; struct timer_list rx_timeout; char name[64]; char phys[64]; -- 2.20.1