Syzbot identified a refcount leak in the hid-elo driver:
BUG: memory leak
unreferenced object 0xffff88810d49e800 (size 2048):
comm "kworker/1:1", pid 25, jiffies 4294954629 (age 16.460s)
hex dump (first 32 bytes):
ff ff ff ff 31 00 00 00 00 00 00 00 00 00 00 00 ....1...........
00 00 00 00 00 00 00 00 00 00 00 00 03 00 00 00 ................
backtrace:
[<ffffffff82c87a62>] kmalloc include/linux/slab.h:581 [inline]
[<ffffffff82c87a62>] kzalloc include/linux/slab.h:715 [inline]
[<ffffffff82c87a62>] usb_alloc_dev+0x32/0x450 drivers/usb/core/usb.c:582
[<ffffffff82c91a47>] hub_port_connect drivers/usb/core/hub.c:5260 [inline]
[<ffffffff82c91a47>] hub_port_connect_change drivers/usb/core/hub.c:5502 [inline]
[<ffffffff82c91a47>] port_event drivers/usb/core/hub.c:5660 [inline]
[<ffffffff82c91a47>] hub_event+0x1097/0x21a0 drivers/usb/core/hub.c:5742
[<ffffffff8126c3ef>] process_one_work+0x2bf/0x600 kernel/workqueue.c:2307
[<ffffffff8126ccd9>] worker_thread+0x59/0x5b0 kernel/workqueue.c:2454
[<ffffffff81276765>] kthread+0x125/0x160 kernel/kthread.c:377
[<ffffffff810022ff>] ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Not shown in the bug report but present in the console log:
[ 182.014764][ T3257] elo 0003:04E7:0030.0006: item fetching failed at offset 0/1
[ 182.022255][ T3257] elo 0003:04E7:0030.0006: parse failed
[ 182.027904][ T3257] elo: probe of 0003:04E7:0030.0006 failed with error -22
[ 182.214767][ T3257] usb 1-1: USB disconnect, device number 7
[ 188.090199][ T3604] kmemleak: 3 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
BUG: memory leak
which points to hid-elo as the buggy driver.
The leak is caused by elo_probe() failing to release the reference it
holds to the struct usb_device in its failure pathway. In the end the
driver doesn't need to take this reference at all, because the
elo_priv structure is always deallocated synchronously when the driver
unbinds from the interface.
Therefore this patch fixes the reference leak by not taking the
reference in the first place.
Reported-and-tested-by: syzbot+8caaaec4e7a55d75e243@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
---
[as1971]
drivers/hid/hid-elo.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
Index: usb-devel/drivers/hid/hid-elo.c
===================================================================
--- usb-devel.orig/drivers/hid/hid-elo.c
+++ usb-devel/drivers/hid/hid-elo.c
@@ -239,7 +239,7 @@ static int elo_probe(struct hid_device *
INIT_DELAYED_WORK(&priv->work, elo_work);
udev = interface_to_usbdev(to_usb_interface(hdev->dev.parent));
- priv->usbdev = usb_get_dev(udev);
+ priv->usbdev = udev;
hid_set_drvdata(hdev, priv);
@@ -270,8 +270,6 @@ static void elo_remove(struct hid_device
{
struct elo_priv *priv = hid_get_drvdata(hdev);
- usb_put_dev(priv->usbdev);
-
hid_hw_stop(hdev);
cancel_delayed_work_sync(&priv->work);
kfree(priv);
