Re: [PATCH -next V2 1/2] sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 2021/11/22 11:03, libaokun (A) wrote:
> 在 2021/11/20 20:01, Sergei Shtylyov 写道:
>> Hello!
>>
>> On 20.11.2021 6:34, Baokun Li wrote:
>>
>>> When the `rmmod sata_fsl.ko` command is executed in the PPC64 GNU/Linux,
>>> a bug is reported:
>>>   ==================================================================
>>>   BUG: Unable to handle kernel data access on read at 0x80000800805b502c
>>>   Oops: Kernel access of bad area, sig: 11 [#1]
>>>   NIP [c0000000000388a4] .ioread32+0x4/0x20
>>>   LR [80000000000c6034] .sata_fsl_port_stop+0x44/0xe0 [sata_fsl]
>>>   Call Trace:
>>>    .free_irq+0x1c/0x4e0 (unreliable)
>>>    .ata_host_stop+0x74/0xd0 [libata]
>>>    .release_nodes+0x330/0x3f0
>>>    .device_release_driver_internal+0x178/0x2c0
>>>    .driver_detach+0x64/0xd0
>>>    .bus_remove_driver+0x70/0xf0
>>>    .driver_unregister+0x38/0x80
>>>    .platform_driver_unregister+0x14/0x30
>>>    .fsl_sata_driver_exit+0x18/0xa20 [sata_fsl]
>>>    .__se_sys_delete_module+0x1ec/0x2d0
>>>    .system_call_exception+0xfc/0x1f0
>>>    system_call_common+0xf8/0x200
>>>   ==================================================================
>>>
>>> The triggering of the BUG is shown in the following stack:
>>>
>>> driver_detach
>>>    device_release_driver_internal
>>>      __device_release_driver
>>>        drv->remove(dev) --> platform_drv_remove/platform_remove
>>>          drv->remove(dev) --> sata_fsl_remove
>>>            iounmap(host_priv->hcr_base);            <---- unmap
>>>            kfree(host_priv);                             <---- free
>>>        devres_release_all
>>>          release_nodes
>>>            dr->node.release(dev, dr->data) --> ata_host_stop
>>>              ap->ops->port_stop(ap) --> sata_fsl_port_stop
>>>                  ioread32(hcr_base + HCONTROL)           <---- UAF
>>>              host->ops->host_stop(host)
>>>
>>> The iounmap(host_priv->hcr_base) and kfree(host_priv) commands should
>>
>>   s/commands/functions/?
> 
> OK! I'm going to modify this in V3.
> 
> 
>>
>>> not be executed in drv->remove. These commands should be executed in
>>> host_stop after port_stop. Therefore, we move these commands to the
>>> new function sata_fsl_host_stop and bind the new function to host_stop
>>> by referring to achi.
>>
>>   You mean AHCI? I don't see where you reference ahci (or achi)...
> 
> Yes, it's AHCI, I'm sorry for a spelling error here..
> 
> ahci_platform_ops in drivers/ata/libahci_platform.c
> 
> 
>>
>>> Reported-by: Hulk Robot <hulkci@huawei.com>
>>> Signed-off-by: Baokun Li <libaokun1@huawei.com>
>>
>>   Doesn't this need to go into the stable trees?
> 
> 
> I felt it was needed because the bug was triggered in a very simple way,
> 
> although PPC linux is rare these days.
> 
> And I will add
> 
> Fixes: faf0b2e5afe7 ("drivers/ata: add support to Freescale 3.0Gbps SATA Controller").

Also add:

Cc: stable@vger.kernel.org


> 
>>
>>> ---
>>>   drivers/ata/sata_fsl.c | 17 ++++++++++++++---
>>>   1 file changed, 14 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/ata/sata_fsl.c b/drivers/ata/sata_fsl.c
>>> index e5838b23c9e0..30759fd1c3a2 100644
>>> --- a/drivers/ata/sata_fsl.c
>>> +++ b/drivers/ata/sata_fsl.c
>>> @@ -1430,12 +1430,25 @@ static struct ata_port_operations sata_fsl_ops = {
>>>       .pmp_detach = sata_fsl_pmp_detach,
>>>   };
>>>   +static void sata_fsl_host_stop(struct ata_host *host)
>>> +{
>>> +    struct sata_fsl_host_priv *host_priv = host->private_data;
>>> +
>>> +    iounmap(host_priv->hcr_base);
>>> +    kfree(host_priv);
>>> +}
>>> +
>>> +static struct ata_port_operations sata_fsl_platform_ops = {
>>> +    .inherits       = &sata_fsl_ops,
>>> +    .host_stop      = sata_fsl_host_stop,
>>
>>   Why not just add it to the initializer for sata_fsl_ops?
> 
> 
> This is the AHCI of the reference.
> 
> Most ATA drivers add host_stop to to the  initializer for  xxx_platform_ops,
> 
> such as ahci_platform_ops, ahci_brcm_platform_ops, and ahci_imx_ops.
> 
> It feels like this separates the port operation from the host operation,
> 
> making the hierarchy of the code clearer.
> 
> 
>>
>> [...]
>>
>> MBR, Sergei
>> .
> 
> 
> Thank you very much for your advice.
> 
> If there's nothing else to modify, I'll send a patch V3.
> 
> -- 
> With Best Regards,
> Baokun Li
> .
> 


-- 
Damien Le Moal
Western Digital Research