Re: [PATCH v2] kobject: Fix slab-out-of-bounds in fill_kobj_path()

[Wang Hai]

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@xxxxxxxxxx>
> > > ---
> > 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