lkml.org 
[lkml]   [2009]   [Aug]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[patch 31/34] vmur: Invalid allocation sequence for vmur class
    From: Michael Holzheu <holzheu@linux.vnet.ibm.com>

    The vmur class is allocated after the CCW driver is registered
    and it is destroyed before the CCW driver is unregistered.
    This is not the correct sequence, because the vmur class can be used
    via driver core callbacks that are triggered during the CCW driver
    deregistration. For Example:

    1. vmur device is online
    2. vmur module is unloaded

    This leads to the following function call stack:

    <4> [<0000000000387286>] device_destroy+0x36/0x5c
    <4> [<000003e000209714>] ur_set_offline_force+0x9c/0x10c [vmur]
    <4> [<000003e00020a928>] ur_remove+0x64/0xbc [vmur]
    <4> [<00000000003e4d2e>] ccw_device_remove+0x42/0x1ac
    <4> [<000000000038a1aa>] __device_release_driver+0x9a/0xe4
    <4> [<000000000038a2da>] driver_detach+0xe6/0xec
    <4> [<0000000000388ee4>] bus_remove_driver+0xc0/0x108
    <4> [<000003e00020ad5a>] ur_exit+0x52/0x84 [vmur]

    In device_destroy() the vmur class is used. Since it is already freed,
    this can lead to a kernel panic.

    To fix the problem, the vmur class has to be allocated before the CCW
    driver is registered and destroyed after the CCW driver has ben unregistered.

    Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
    Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
    ---

    drivers/s390/char/vmur.c | 19 ++++++++++---------
    1 file changed, 10 insertions(+), 9 deletions(-)

    Index: quilt-2.6/drivers/s390/char/vmur.c
    ===================================================================
    --- quilt-2.6.orig/drivers/s390/char/vmur.c
    +++ quilt-2.6/drivers/s390/char/vmur.c
    @@ -1026,9 +1026,15 @@ static int __init ur_init(void)

    debug_set_level(vmur_dbf, 6);

    + vmur_class = class_create(THIS_MODULE, "vmur");
    + if (IS_ERR(vmur_class)) {
    + rc = PTR_ERR(vmur_class);
    + goto fail_free_dbf;
    + }
    +
    rc = ccw_driver_register(&ur_driver);
    if (rc)
    - goto fail_free_dbf;
    + goto fail_class_destroy;

    rc = alloc_chrdev_region(&dev, 0, NUM_MINORS, "vmur");
    if (rc) {
    @@ -1038,18 +1044,13 @@ static int __init ur_init(void)
    }
    ur_first_dev_maj_min = MKDEV(MAJOR(dev), 0);

    - vmur_class = class_create(THIS_MODULE, "vmur");
    - if (IS_ERR(vmur_class)) {
    - rc = PTR_ERR(vmur_class);
    - goto fail_unregister_region;
    - }
    pr_info("%s loaded.\n", ur_banner);
    return 0;

    -fail_unregister_region:
    - unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
    fail_unregister_driver:
    ccw_driver_unregister(&ur_driver);
    +fail_class_destroy:
    + class_destroy(vmur_class);
    fail_free_dbf:
    debug_unregister(vmur_dbf);
    return rc;
    @@ -1057,9 +1058,9 @@ fail_free_dbf:

    static void __exit ur_exit(void)
    {
    - class_destroy(vmur_class);
    unregister_chrdev_region(ur_first_dev_maj_min, NUM_MINORS);
    ccw_driver_unregister(&ur_driver);
    + class_destroy(vmur_class);
    debug_unregister(vmur_dbf);
    pr_info("%s unloaded.\n", ur_banner);
    }
    --
    blue skies,
    Martin.

    "Reality continues to ruin my life." - Calvin.



    \
     
     \ /
      Last update: 2009-08-14 13:57    [W:0.044 / U:1.260 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site