[PATCH 4.19 111/113] PCI: hv: Fix a memory leak in hv_eject_device_work()

From: Greg Kroah-Hartman
Date: Wed May 15 2019 - 07:27:28 EST

From: Dexuan Cui <decui@xxxxxxxxxxxxx>

commit 05f151a73ec2b23ffbff706e5203e729a995cdc2 upstream.

When a device is created in new_pcichild_device(), hpdev->refs is set
to 2 (i.e. the initial value of 1 plus the get_pcichild()).

When we hot remove the device from the host, in a Linux VM we first call
hv_pci_eject_device(), which increases hpdev->refs by get_pcichild() and
then schedules a work of hv_eject_device_work(), so hpdev->refs becomes
3 (let's ignore the paired get/put_pcichild() in other places). But in
hv_eject_device_work(), currently we only call put_pcichild() twice,
meaning the 'hpdev' struct can't be freed in put_pcichild().

Add one put_pcichild() to fix the memory leak.

The device can also be removed when we run "rmmod pci-hyperv". On this
path (hv_pci_remove() -> hv_pci_bus_exit() -> hv_pci_devices_present()),
hpdev->refs is 2, and we do correctly call put_pcichild() twice in

Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs")
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
[lorenzo.pieralisi@xxxxxxx: commit log rework]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Reviewed-by: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/pci/controller/pci-hyperv.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1905,6 +1905,9 @@ static void hv_eject_device_work(struct
sizeof(*ejct_pkt), (unsigned long)&ctxt.pkt,

+ /* For the get_pcichild() in hv_pci_eject_device() */
+ put_pcichild(hpdev);
+ /* For the two refs got in new_pcichild_device() */