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

[Wang Hai <wanghai38@huawei.com>]

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@huawei.com>
> ---
Hi, greg k-h.
Sorry to bother you. Can this patch be merged into the mainline?

-- 
Wang Hai