linux-kernel - Re: [PATCH v2] kobject: Fix slab-out-of-bounds in fill_kobj

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Date:   Mon, 9 Jan 2023 19:15:05 +0800
From:   Wang Hai <wanghai38@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <intel-wired-lan@...ts.osuosl.org>, <linux-kernel@...r.kernel.org>,
        <anthony.l.nguyen@...el.com>, <rafael@...nel.org>,
        <jesse.brandeburg@...el.com>, <alice.chao@...iatek.com>
Subject: Re: [PATCH v2] kobject: Fix slab-out-of-bounds in fill_kobj_path()


在 2023/1/9 18:33, Greg KH 写道:
> On Mon, Jan 09, 2023 at 05:37:23PM +0800, Wang Hai wrote:
>> 在 2022/12/20 9:21, Wang Hai 写道:
>>> In kobject_get_path(), if kobj->name is changed between calls
>>> get_kobj_path_length() and fill_kobj_path() and the length becomes
>>> longer, then fill_kobj_path() will have an out-of-bounds bug.
>>>
>>> The actual current problem occurs when the ixgbe probe.
>>>
>>> In ixgbe_mii_bus_init(), if the length of netdev->dev.kobj.name
>>> length becomes longer, out-of-bounds will occur.
>>>
>>> cpu0                                         cpu1
>>> ixgbe_probe
>>>    register_netdev(netdev)
>>>     netdev_register_kobject
>>>      device_add
>>>       kobject_uevent // Sending ADD events
>>>                                                systemd-udevd // rename netdev
>>>                                                 dev_change_name
>>>                                                  device_rename
>>>                                                   kobject_rename
>>>    ixgbe_mii_bus_init                             |
>>>     mdiobus_register                              |
>>>      __mdiobus_register                           |
>>>       device_register                             |
>>>        device_add                                 |
>>>         kobject_uevent                            |
>>>          kobject_get_path                         |
>>>           len = get_kobj_path_length // old name  |
>>>           path = kzalloc(len, gfp_mask);          |
>>>                                                   kobj->name = name;
>>>                                                   /* name length becomes
>>>                                                    * longer
>>>                                                    */
>>>           fill_kobj_path /* kobj path length is
>>>                           * longer than path,
>>>                           * resulting in out of
>>>                           * bounds when filling path
>>>                           */
>>>
>>> This is the kasan report:
>>>
>>> ==================================================================
>>> BUG: KASAN: slab-out-of-bounds in fill_kobj_path+0x50/0xc0
>>> Write of size 7 at addr ff1100090573d1fd by task kworker/28:1/673
>>>
>>>    Workqueue: events work_for_cpu_fn
>>>    Call Trace:
>>>    <TASK>
>>>    dump_stack_lvl+0x34/0x48
>>>    print_address_description.constprop.0+0x86/0x1e7
>>>    print_report+0x36/0x4f
>>>    kasan_report+0xad/0x130
>>>    kasan_check_range+0x35/0x1c0
>>>    memcpy+0x39/0x60
>>>    fill_kobj_path+0x50/0xc0
>>>    kobject_get_path+0x5a/0xc0
>>>    kobject_uevent_env+0x140/0x460
>>>    device_add+0x5c7/0x910
>>>    __mdiobus_register+0x14e/0x490
>>>    ixgbe_probe.cold+0x441/0x574 [ixgbe]
>>>    local_pci_probe+0x78/0xc0
>>>    work_for_cpu_fn+0x26/0x40
>>>    process_one_work+0x3b6/0x6a0
>>>    worker_thread+0x368/0x520
>>>    kthread+0x165/0x1a0
>>>    ret_from_fork+0x1f/0x30
>>>
>>> This reproducer triggers that bug:
>>>
>>> while:
>>> do
>>>       rmmod ixgbe
>>>       sleep 0.5
>>>       modprobe ixgbe
>>>       sleep 0.5
>>>
>>> When calling fill_kobj_path() to fill path, if the name length of
>>> kobj becomes longer, return failure and retry. This fixes the problem.
>>>
>>> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
>>> Signed-off-by: Wang Hai <wanghai38@...wei.com>
>>> ---
>> Hi, greg k-h.
>> Sorry to bother you. Can this patch be merged into the mainline?
> It's in my "to review" queue that I am working on.  As this is not
> anything that a normal user can trigger, it's not that high of a
> priority, right?
>
> thanks,
>
> greg k-h
> .
Thanks, I thought you had forgotten about it. I hope I'm not disturbing you.

-- 
Wang Hai