• Roderick Colenbrander's avatar
    HID: sony: Fix race condition between rumble and device remove. · bba097c4
    Roderick Colenbrander authored
    commit e0f6974a upstream.
    
    Valve reported a kernel crash on Ubuntu 18.04 when disconnecting a DS4
    gamepad while rumble is enabled. This issue is reproducible with a
    frequency of 1 in 3 times in the game Borderlands 2 when using an
    automatic weapon, which triggers many rumble operations.
    
    We found the issue to be a race condition between sony_remove and the
    final device destruction by the HID / input system. The problem was
    that sony_remove didn't clean some of its work_item state in
    "struct sony_sc". After sony_remove work, the corresponding evdev
    node was around for sufficient time for applications to still queue
    rumble work after "sony_remove".
    
    On pre-4.19 kernels the race condition caused a kernel crash due to a
    NULL-pointer dereference as "sc->output_report_dmabuf" got freed during
    sony_remove. On newer kernels this crash doesn't happen due the buffer
    now being allocated using devm_kzalloc. However we can still queue work,
    while the driver is an undefined state.
    
    This patch fixes the described problem, by guarding the work_item
    "state_worker" with an initialized variable, which we are setting back
    to 0 on cleanup.
    Signed-off-by: default avatarRoderick Colenbrander <roderick.colenbrander@sony.com>
    CC: stable@vger.kernel.org
    Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    bba097c4
hid-sony.c 90.6 KB