[PATCH] HID: magicmouse: Fix an error handling path in magicmouse_probe()

If the timer introduced by the commit below is started, then it must be
deleted in the error handling of the probe. Otherwise it would trigger
once the driver is no more.

Fixes: 0b91b4e4dae6 ("HID: magicmouse: Report battery level over USB")
Signed-off-by: Christophe JAILLET <redacted>
---
 drivers/hid/hid-magicmouse.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index eba1e8087bfd..b8b08f0a8c54 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c

@@ -873,6 +873,7 @@ static int magicmouse_probe(struct hid_device *hdev,
 
 	return 0;
 err_stop_hw:
+	del_timer_sync(&msc->battery_timer);
 	hid_hw_stop(hdev);
 	return ret;
 }

-- 
2.32.0

On Tue, Dec 28, 2021 at 10:09:17PM +0100, Christophe JAILLET wrote:

My bad, thanks for catching it!

Tested-by: José Expósito <redacted>

Le 29/12/2021 à 08:50, José Expósito a écrit :

On Tue, Dec 28, 2021 at 10:09:17PM +0100, Christophe JAILLET wrote:

quoted

If the timer introduced by the commit below is started, then it must be
deleted in the error handling of the probe. Otherwise it would trigger
once the driver is no more.

Fixes: 0b91b4e4dae6 ("HID: magicmouse: Report battery level over USB")
Signed-off-by: Christophe JAILLET <redacted>
---
  drivers/hid/hid-magicmouse.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index eba1e8087bfd..b8b08f0a8c54 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c

@@ -873,6 +873,7 @@ static int magicmouse_probe(struct hid_device *hdev,
  
  	return 0;
  err_stop_hw:
+	del_timer_sync(&msc->battery_timer);
  	hid_hw_stop(hdev);
  	return ret;
  }

-- 
2.32.0

My bad, thanks for catching it!

Tested-by: José Expósito <redacted>

Hi, just in case, I got a reply from syzbot that this patch fixes:

https://syzkaller.appspot.com/bug?id=ae4e9aaf5651e1d6895071208c7844d4fdfbe30c

If it is the same issue, we can add:
Reported-by: syzbot+a437546ec71b04dfb5ac@syzkaller.appspotmail.com


I've not found it with syzbot, but with a coccinelle script which tries 
to spot things that are in the remove function and should also be in the 
error handling path of the probe.

However, if it help syzbot, I don't care mentioning it.

CJ

On Tue, 28 Dec 2021, Christophe JAILLET wrote:

Applied, thanks.

-- 
Jiri Kosina
SUSE Labs