From: "libaokun (A)" <libaokun1@huawei.com>
To: Sergei Shtylyov <sergei.shtylyov@gmail.com>,
<damien.lemoal@opensource.wdc.com>, <axboe@kernel.dk>,
<tj@kernel.org>, <linux-ide@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: <yebin10@huawei.com>, <yukuai3@huawei.com>,
Hulk Robot <hulkci@huawei.com>
Subject: Re: [PATCH -next V2 1/2] sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl
Date: Tue, 23 Nov 2021 09:11:52 +0800 [thread overview]
Message-ID: <7d7bf674-5268-98bc-ba70-be97cce396d5@huawei.com> (raw)
In-Reply-To: <e9d66318-3b5d-f737-ec7a-d819c4aa5b6b@gmail.com>
在 2021/11/23 2:58, Sergei Shtylyov 写道:
> Hello!
>
> On 22.11.2021 5:03, libaokun (A) 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
>
> You should have (at least) written "the AHCI platform driver"...
>
> [...]
>>>> 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,
>
> Most? Even if so, I guess they add it this way because they're in
> the separate modules with the ops they inherit -- in this case it's
> not so.
>
>> such as ahci_platform_ops, ahci_brcm_platform_ops, and ahci_imx_ops.
>
> Note that these are all AHCI drivers, not just (more general) ATA.
>
>> It feels like this separates the port operation from the host operation,
>
> Why separate them? The 'struct ata_port_operations' embraces many
> different aspects of ATA, the arguments do not always include a
> 'struct *ata_port' (I don't quite like that part in libata).
>
>> making the hierarchy of the code clearer.
>
> Clear as mud. In your case, there's no separate modules in play, so
> blindly parroting what the AHCI platform drivers do gives you nothing
> but memory waste... :-(
>
>>> [...]
>>>
>>> MBR, Sergei
>>> .
>>
>>
>> Thank you very much for your advice.
>
> You're welcome. :-)
>
>> If there's nothing else to modify, I'll send a patch V3.
>
> Please use a single structure, it's already large enough to have 2
> of them in the same module for no good reason.
>
>> --
>> With Best Regards,
>> Baokun Li
>
> MBR, Sergei
> .
Thank you very much for your advice.
I'm about to send a patch V4 with the changes suggested by you.
--
With Best Regards,
Baokun Li
next prev parent reply other threads:[~2021-11-23 1:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-20 3:34 [PATCH -next V2 0/2] fix two bugs when trying rmmod sata_fsl Baokun Li
2021-11-20 3:34 ` [PATCH -next V2 1/2] sata_fsl: fix UAF in sata_fsl_port_stop when " Baokun Li
2021-11-20 12:01 ` Sergei Shtylyov
[not found] ` <4d2712d3-00a1-6220-0a86-8580b2f89d03@huawei.com>
2021-11-22 2:33 ` Damien Le Moal
2021-11-22 2:50 ` libaokun (A)
2021-11-22 18:58 ` Sergei Shtylyov
2021-11-23 1:11 ` libaokun (A) [this message]
2021-11-20 3:34 ` [PATCH -next V2 2/2] sata_fsl: fix warning in remove_proc_entry " Baokun Li
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