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    usb: core: safely deal with the dynamic quirk lists · 16c4cb19
    Harry Pan authored
    Applying dynamic usbcore quirks in early booting when the slab is
    not yet ready would cause kernel panic of null pointer dereference
    because the quirk_count has been counted as 1 while the quirk_list
    was failed to allocate.
    
    i.e.,
    [    1.044970] BUG: unable to handle kernel NULL pointer dereference at           (null)
    [    1.044995] IP: [<ffffffffb0953ec7>] usb_detect_quirks+0x88/0xd1
    [    1.045016] PGD 0
    [    1.045026] Oops: 0000 [#1] PREEMPT SMP
    [    1.046986] gsmi: Log Shutdown Reason 0x03
    [    1.046995] Modules linked in:
    [    1.047008] CPU: 0 PID: 81 Comm: kworker/0:3 Not tainted 4.4.154 #28
    [    1.047016] Hardware name: Google Coral/Coral, BIOS Google_Coral.10068.27.0 12/04/2017
    [    1.047028] Workqueue: usb_hub_wq hub_event
    [    1.047037] task: ffff88017a321c80 task.stack: ffff88017a384000
    [    1.047044] RIP: 0010:[<ffffffffb0953ec7>]  [<ffffffffb0953ec7>] usb_detect_quirks+0x88/0xd1
    
    To tackle this odd, let's balance the quirk_count to 0 when the kcalloc
    call fails, and defer the quirk setting into a lower level callback
    which ensures that the kernel memory management has been initialized.
    
    Fixes: 027bd6ca
    
     ("usb: core: Add "quirks" parameter for usbcore")
    Signed-off-by: default avatarHarry Pan <harry.pan@intel.com>
    Acked-by: default avatarKai-Heng Feng <kai.heng.feng@canonical.com>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    16c4cb19