• Alex Williamson's avatar
    driver core: Fix unbalanced device reference in drivers_probe · bdf2a0db
    Alex Williamson authored
    commit bb34cb6bbd287b57e955bc5cfd42fcde6aaca279 upstream.
    
    bus_find_device_by_name() acquires a device reference which is never
    released.  This results in an object leak, which on older kernels
    results in failure to release all resources of PCI devices.  libvirt
    uses drivers_probe to re-attach devices to the host after assignment
    and is therefore a common trigger for this leak.
    
    Example:
    
    # cd /sys/bus/pci/
    # dmesg -C
    # echo 1 > devices/0000\:01\:00.0/sriov_numvfs
    # echo 0 > devices/0000\:01\:00.0/sriov_numvfs
    # dmesg | grep 01:10
     pci 0000:01:10.0: [8086:10ca] type 00 class 0x020000
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): kobject_add_internal: parent: '0000:00:01.0', set: 'devices'
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): kobject_uevent_env
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): fill_kobj_path: path = '/devices/pci0000:00/0000:00:01.0/0000:01:10.0'
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): kobject_uevent_env
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): fill_kobj_path: path = '/devices/pci0000:00/0000:00:01.0/0000:01:10.0'
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): kobject_uevent_env
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): fill_kobj_path: path = '/devices/pci0000:00/0000:00:01.0/0000:01:10.0'
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): kobject_cleanup, parent           (null)
     kobject: '0000:01:10.0' (ffff8801d79cd0a8): calling ktype release
     kobject: '0000:01:10.0': free name
    
    [kobject freed as expected]
    
    # dmesg -C
    # echo 1 > devices/0000\:01\:00.0/sriov_numvfs
    # echo 0000:01:10.0 > drivers_probe
    # echo 0 > devices/0000\:01\:00.0/sriov_numvfs
    # dmesg | grep 01:10
     pci 0000:01:10.0: [8086:10ca] type 00 class 0x020000
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): kobject_add_internal: parent: '0000:00:01.0', set: 'devices'
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): kobject_uevent_env
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): fill_kobj_path: path = '/devices/pci0000:00/0000:00:01.0/0000:01:10.0'
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): kobject_uevent_env
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): fill_kobj_path: path = '/devices/pci0000:00/0000:00:01.0/0000:01:10.0'
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): kobject_uevent_env
     kobject: '0000:01:10.0' (ffff8801d79ce0a8): fill_kobj_path: path = '/devices/pci0000:00/0000:00:01.0/0000:01:10.0'
    
    [no free]
    Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    bdf2a0db
bus.c 32.3 KB