linux-kernel - Re: [PATCH v2] dma-buf: acquire name lock before read/write dma

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Message-ID: <ba926a86-1262-00ae-87d3-fa4150a1eb3a@amd.com>
Date:   Fri, 29 Oct 2021 09:34:53 +0200
From:   Christian König <christian.koenig@....com>
To:     guangming.cao@...iatek.com
Cc:     dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        matthias.bgg@...il.com, sumit.semwal@...aro.org,
        wsd_upstream@...iatek.com
Subject: Re: [PATCH v2] dma-buf: acquire name lock before read/write
 dma_buf.name



Am 29.10.21 um 04:15 schrieb guangming.cao@...iatek.com:
> From: Guangming Cao <Guangming.Cao@...iatek.com>
>
> On Fri, 2021-10-08 at 12:24 +0200, Christian König wrote:
>> Am 08.10.21 um 09:54 schrieb guangming.cao@...iatek.com:
>>> From: Guangming Cao <Guangming.Cao@...iatek.com>
>>>
>>> Because dma-buf.name can be freed in func: "dma_buf_set_name",
>>> so, we need to acquire lock first before we read/write dma_buf.name
>>> to prevent Use After Free(UAF) issue.
>>>
>>> Signed-off-by: Guangming Cao <Guangming.Cao@...iatek.com>
>> Reviewed-by: Christian König <christian.koenig@....com>
>>
>> Going to push that upstream if nobody else objects.
>>
>> Thanks,
>> Christian.
> Just a gentle ping for this patch, please kindly let me know how is it going.

Ah, yes. Thanks for the reminder.

I've just pushed this to drm-misc-fixes.

Christian.

>
>>> ---
>>>    drivers/dma-buf/dma-buf.c | 3 +++
>>>    1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
>>> index 511fe0d217a0..a7f6fd13a635 100644
>>> --- a/drivers/dma-buf/dma-buf.c
>>> +++ b/drivers/dma-buf/dma-buf.c
>>> @@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file
>>> *s, void *unused)
>>>    		if (ret)
>>>    			goto error_unlock;
>>>    
>>> +
>>> +		spin_lock(&buf_obj->name_lock);
>>>    		seq_printf(s,
>>> "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
>>>    				buf_obj->size,
>>>    				buf_obj->file->f_flags, buf_obj->file-
>>>> f_mode,
>>> @@ -1379,6 +1381,7 @@ static int dma_buf_debug_show(struct seq_file
>>> *s, void *unused)
>>>    				buf_obj->exp_name,
>>>    				file_inode(buf_obj->file)->i_ino,
>>>    				buf_obj->name ?: "");
>>> +		spin_unlock(&buf_obj->name_lock);
>>>    
>>>    		robj = buf_obj->resv;
>>>    		fence = dma_resv_excl_fence(robj);
>>
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