[Qemu-devel] Something wrong in usb_try_create_simple()

[Thomas Huth]

 Hi Gerd,

today, I've run into this issue reported by valgrind:

$ valgrind x86_64-softmmu/qemu-system-x86_64 -device usb-ehci -nographic -S
==2043== Memcheck, a memory error detector
==2043== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==2043== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
==2043== Command: x86_64-softmmu/qemu-system-x86_64 -device usb-ehci -nographic 
-S
==2043== 
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
==2043== Invalid read of size 8
==2043==    at 0x60EF50: object_unparent (object.c:445)
==2043==    by 0x580F0D: usb_try_create_simple (bus.c:346)
==2043==    by 0x581BEB: usb_claim_port (bus.c:451)
==2043==    by 0x582310: usb_qdev_realize (bus.c:257)
==2043==    by 0x4CB399: device_set_realized (qdev.c:914)
==2043==    by 0x60E26D: property_set_bool (object.c:1886)
==2043==    by 0x61235E: object_property_set_qobject (qom-qobject.c:27)
==2043==    by 0x61000F: object_property_set_bool (object.c:1162)
==2043==    by 0x4567C3: qdev_device_add (qdev-monitor.c:630)
==2043==    by 0x456D52: qmp_device_add (qdev-monitor.c:807)
==2043==    by 0x470A99: hmp_device_add (hmp.c:1933)
==2043==    by 0x3679C3: handle_hmp_command (monitor.c:3123)
==2043==  Address 0x2100b430 is 32 bytes inside a block of size 6,448 free'd
==2043==    at 0x4C2ACDD: free (vg_replace_malloc.c:530)
==2043==    by 0xA04EBCD: g_free (in /usr/lib64/libglib-2.0.so.0.5000.3)
==2043==    by 0x60F735: object_finalize (object.c:471)
==2043==    by 0x60F735: object_unref (object.c:902)
==2043==    by 0x60E746: object_property_del_child.isra.7 (object.c:427)
==2043==    by 0x4CB2B2: device_set_realized (qdev.c:994)
==2043==    by 0x60E26D: property_set_bool (object.c:1886)
==2043==    by 0x61235E: object_property_set_qobject (qom-qobject.c:27)
==2043==    by 0x61000F: object_property_set_bool (object.c:1162)
==2043==    by 0x580EBB: usb_try_create_simple (bus.c:341)
==2043==    by 0x581BEB: usb_claim_port (bus.c:451)
==2043==    by 0x582310: usb_qdev_realize (bus.c:257)
==2043==    by 0x4CB399: device_set_realized (qdev.c:914)
==2043==  Block was alloc'd at
==2043==    at 0x4C29BE3: malloc (vg_replace_malloc.c:299)
==2043==    by 0xA04EABD: g_malloc (in /usr/lib64/libglib-2.0.so.0.5000.3)
==2043==    by 0x60EE0C: object_new_with_type (object.c:482)
==2043==    by 0x4CA080: qdev_try_create (qdev.c:152)
==2043==    by 0x580E7A: usb_try_create_simple (bus.c:336)
==2043==    by 0x581BEB: usb_claim_port (bus.c:451)
==2043==    by 0x582310: usb_qdev_realize (bus.c:257)
==2043==    by 0x4CB399: device_set_realized (qdev.c:914)
==2043==    by 0x60E26D: property_set_bool (object.c:1886)
==2043==    by 0x61235E: object_property_set_qobject (qom-qobject.c:27)
==2043==    by 0x61000F: object_property_set_bool (object.c:1162)
==2043==    by 0x4567C3: qdev_device_add (qdev-monitor.c:630)

Any idea what could be wrong here?

 Thomas