• Alex Chiang's avatar
    PCI Hotplug: acpiphp: don't store a pci_dev in acpiphp_func · 9d911d79
    Alex Chiang authored
    An oops can occur if a user attempts to use both PCI logical
    hotplug and the ACPI physical hotplug driver (acpiphp) in this
    sequence, where $slot/address == $device.
    
    In other words, if acpiphp has claimed a PCI device, and that
    device is logically removed, then acpiphp may oops when it
    attempts to access it again.
    
    	# echo 1 > /sys/bus/pci/devices/$device/remove
    	# echo 0 > /sys/bus/pci/slots/$slot/power
    
    Unable to handle kernel NULL pointer dereference (address 0000000000000000)
    Call Trace:
     [<a000000100016390>] show_stack+0x50/0xa0
     [<a000000100016c60>] show_regs+0x820/0x860
     [<a00000010003b390>] die+0x190/0x2a0
     [<a000000100066a40>] ia64_do_page_fault+0x8e0/0xa40
     [<a00000010000c7a0>] ia64_native_leave_kernel+0x0/0x270
     [<a0000001003b2660>] pci_remove_bus_device+0x120/0x260
     [<a0000002060549f0>] acpiphp_disable_slot+0x410/0x540 [acpiphp]
     [<a0000002060505c0>] disable_slot+0xc0/0x120 [acpiphp]
     [<a0000002040d21c0>] power_write_file+0x1e0/0x2a0 [pci_hotplug]
     [<a0000001003bb820>] pci_slot_attr_store+0x60/0xa0
     [<a000000100240f70>] sysfs_write_file+0x230/0x2c0
     [<a000000100195750>] vfs_write+0x190/0x2e0
     [<a0000001001961a0>] sys_write+0x80/0x100
     [<a00000010000c600>] ia64_ret_from_syscall+0x0/0x20
     [<a000000000010720>] __kernel_syscall_via_break+0x0/0x20
    
    The root cause of this oops is that the logical remove ("echo 1 >
    /sys/bus/pci/devices/$device/remove") destroyed the pci_dev. The
    pci_dev struct itself wasn't deallocated because acpiphp kept a
    reference, but some of its fields became invalid.
    
    acpiphp doesn't have any real reason to keep a pointer to a
    pci_dev around. It can always derive it using pci_get_slot().
    
    If a logical remove destroys the pci_dev, acpiphp won't find it
    and is thus prevented from causing mischief.
    Reviewed-by: default avatarMatthew Wilcox <willy@linux.intel.com>
    Reviewed-by: default avatarKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
    Tested-by: default avatarKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
    Reported-by: default avatarKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
    Acked-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
    Signed-off-by: default avatarAlex Chiang <achiang@hp.com>
    Signed-off-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
    9d911d79
acpiphp_glue.c 43.4 KB