Re: [PATCH 4/4] media: venus: hfi: add a check to handle OOB in sfr region

[Vikash Garodia]

On 11/5/2024 7:28 PM, Dmitry Baryshkov wrote:
> On Tue, Nov 05, 2024 at 02:24:57PM +0530, Vikash Garodia wrote:
>> sfr->buf_size is in shared memory and can be modified by malicious user.
>> OOB write is possible when the size is made higher than actual sfr data
>> buffer.
>>
>> Cc: stable@xxxxxxxxxxxxxxx
>> Fixes: d96d3f30c0f2 ("[media] media: venus: hfi: add Venus HFI files")
>> Signed-off-by: Vikash Garodia <quic_vgarodia@xxxxxxxxxxx>
>> ---
>>  drivers/media/platform/qcom/venus/hfi_venus.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/media/platform/qcom/venus/hfi_venus.c b/drivers/media/platform/qcom/venus/hfi_venus.c
>> index 50d92214190d88eff273a5ba3f95486f758bcc05..c19d6bf686d0f31c6a2f551de3f7eb08031bde85 100644
>> --- a/drivers/media/platform/qcom/venus/hfi_venus.c
>> +++ b/drivers/media/platform/qcom/venus/hfi_venus.c
>> @@ -1041,18 +1041,23 @@ static void venus_sfr_print(struct venus_hfi_device *hdev)
>>  {
>>  	struct device *dev = hdev->core->dev;
>>  	struct hfi_sfr *sfr = hdev->sfr.kva;
>> +	u32 size;
>>  	void *p;
>>  
>>  	if (!sfr)
>>  		return;
>>  
>> -	p = memchr(sfr->data, '\0', sfr->buf_size);
>> +	size = sfr->buf_size;
>> +	if (size > ALIGNED_SFR_SIZE)
>> +		return;
> 
> Why can't you just limit size to ALIGNED_SFR_SIZE, still allowing the
> data to be captured?
That should do as well. Updating above check to below would take care of it.
if (size > ALIGNED_SFR_SIZE)
    size = ALIGNED_SFR_SIZE;

Regards,
Vikash
> 
>> +
>> +	p = memchr(sfr->data, '\0', size);
>>  	/*
>>  	 * SFR isn't guaranteed to be NULL terminated since SYS_ERROR indicates
>>  	 * that Venus is in the process of crashing.
>>  	 */
>>  	if (!p)
>> -		sfr->data[sfr->buf_size - 1] = '\0';
>> +		sfr->data[size - 1] = '\0';
>>  
>>  	dev_err_ratelimited(dev, "SFR message from FW: %s\n", sfr->data);
>>  }
>>
>> -- 
>> 2.34.1
>>
>