[Xen-changelog] [qemu-xen stable-4.10] hw/usb/bus: Remove bad object_unparent() from usb_try_create_simple()

[patchbot@xxxxxxx]

commit b23426608629b3ccd263291ffa095f1e8ceadb55
Author:     Thomas Huth <thuth@xxxxxxxxxx>
AuthorDate: Wed Sep 27 17:28:26 2017 +0200
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon Dec 4 20:37:19 2017 -0600

    hw/usb/bus: Remove bad object_unparent() from usb_try_create_simple()
    
    Valgrind detects an invalid read operation when hot-plugging of an
    USB device fails:
    
    $ valgrind x86_64-softmmu/qemu-system-x86_64 -device usb-ehci -nographic -S
    ==30598== Memcheck, a memory error detector
    ==30598== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
    ==30598== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
    ==30598== Command: x86_64-softmmu/qemu-system-x86_64 -device usb-ehci 
-nographic -S
    ==30598==
    QEMU 2.10.50 monitor - type 'help' for more information
    (qemu) device_add usb-tablet
    (qemu) device_add usb-tablet
    (qemu) device_add usb-tablet
    (qemu) device_add usb-tablet
    (qemu) device_add usb-tablet
    (qemu) device_add usb-tablet
    ==30598== Invalid read of size 8
    ==30598==    at 0x60EF50: object_unparent (object.c:445)
    ==30598==    by 0x580F0D: usb_try_create_simple (bus.c:346)
    ==30598==    by 0x581BEB: usb_claim_port (bus.c:451)
    ==30598==    by 0x582310: usb_qdev_realize (bus.c:257)
    ==30598==    by 0x4CB399: device_set_realized (qdev.c:914)
    ==30598==    by 0x60E26D: property_set_bool (object.c:1886)
    ==30598==    by 0x61235E: object_property_set_qobject (qom-qobject.c:27)
    ==30598==    by 0x61000F: object_property_set_bool (object.c:1162)
    ==30598==    by 0x4567C3: qdev_device_add (qdev-monitor.c:630)
    ==30598==    by 0x456D52: qmp_device_add (qdev-monitor.c:807)
    ==30598==    by 0x470A99: hmp_device_add (hmp.c:1933)
    ==30598==    by 0x3679C3: handle_hmp_command (monitor.c:3123)
    
    The object_unparent() here is not necessary anymore since commit
    69382d8b3e8600b3 ("qdev: Fix object reference leak in case device.realize()
    fails"), so let's remove it now.
    
    Suggested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
    Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
    Message-id: 1506526106-30971-1-git-send-email-thuth@xxxxxxxxxx
    Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
    (cherry picked from commit f3b2bea3c76ba9283b957f1373e7cebdbf863059)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 hw/usb/bus.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/hw/usb/bus.c b/hw/usb/bus.c
index d910f84..e56dc33 100644
--- a/hw/usb/bus.c
+++ b/hw/usb/bus.c
@@ -341,9 +341,7 @@ static USBDevice *usb_try_create_simple(USBBus *bus, const 
char *name,
     object_property_set_bool(OBJECT(dev), true, "realized", &err);
     if (err) {
         error_propagate(errp, err);
-        error_prepend(errp, "Failed to initialize USB device '%s': ",
-                      name);
-        object_unparent(OBJECT(dev));
+        error_prepend(errp, "Failed to initialize USB device '%s': ", name);
         return NULL;
     }
     return dev;
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.10

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