• Tang Chen's avatar
    ACPI / hotplug: Check scan handlers in acpi_scan_hot_remove() · dee15926
    Tang Chen authored
    When ACPI_HOTPLUG_MEMORY is not configured, memory_device_handler.attach
    is not set.  In acpi_scan_attach_handler(), the acpi_device->handler will
    not be initialized.
    
    In acpi_scan_hot_remove(), it doesn't check if acpi_device->handler is NULL.
    If we do memory hot-remove without ACPI_HOTPLUG_MEMORY configured, the kernel
    will panic.
    
     BUG: unable to handle kernel NULL pointer dereference at 0000000000000088
     IP: [<ffffffff813e318f>] acpi_device_hotplug+0x1d7/0x4c4
     PGD 0
     Oops: 0000 [#1] SMP
     Modules linked in: sd_mod(E) sr_mod(E) cdrom(E) crc_t10dif(E) crct10dif_common(E) ata_piix(E) libata(E)
     CPU: 0 PID: 41 Comm: kworker/u2:1 Tainted: G            E 3.16.0-rc7--3.16-rc7-tangchen+ #20
     Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
     Workqueue: kacpi_hotplug acpi_hotplug_work_fn
     task: ffff8800182436c0 ti: ffff880018254000 task.ti: ffff880018254000
     RIP: 0010:[<ffffffff813e318f>]  [<ffffffff813e318f>] acpi_device_hotplug+0x1d7/0x4c4
     RSP: 0000:ffff880018257da8  EFLAGS: 00000246
     RAX: 0000000000000000 RBX: ffff88001cd8d800 RCX: 0000000000000000
     RDX: 0000000000000000 RSI: ffff88001e40e6f8 RDI: 0000000000000246
     RBP: ffff880018257df0 R08: 0000000000000096 R09: 00000000000011a0
     R10: 63735f6970636120 R11: 725f746f685f6e61 R12: 0000000000000003
     R13: ffff88001cc1c400 R14: ffff88001e062028 R15: 0000000000000040
     FS:  0000000000000000(0000) GS:ffff88001e400000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
     CR2: 0000000000000088 CR3: 000000001a9a2000 CR4: 00000000000006f0
     DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
     DR3: 0000000000000000 DR6: 0000000000000000 DR7: 0000000000000000
     Stack:
      00000000523cab58 ffff88001cd8d9f8 ffff88001852d480 00000000523cab58
      ffff88001852d480 ffff880018221e40 ffff88001cc1c400 ffff88001cce2d00
      0000000000000040 ffff880018257e08 ffffffff813dc31d ffff88001852d480
     Call Trace:
      [<ffffffff813dc31d>] acpi_hotplug_work_fn+0x1e/0x29
      [<ffffffff8108eefb>] process_one_work+0x17b/0x460
      [<ffffffff8108f69d>] worker_thread+0x11d/0x5b0
      [<ffffffff8108f580>] ? rescuer_thread+0x3a0/0x3a0
      [<ffffffff81096811>] kthread+0xe1/0x100
      [<ffffffff81096730>] ? kthread_create_on_node+0x1a0/0x1a0
      [<ffffffff816cc6bc>] ret_from_fork+0x7c/0xb0
      [<ffffffff81096730>] ? kthread_create_on_node+0x1a0/0x1a0
    
    This patch fixes this problem by checking if acpi_device->handler is NULL
    in acpi_scan_hot_remove().
    
    Fixes: d22ddcbc (ACPI / hotplug: Add demand_offline hotplug profile flag)
    Signed-off-by: default avatarTang Chen <tangchen@cn.fujitsu.com>
    Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
    [rjw: Subject]
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    dee15926
scan.c 58.7 KB