Re: [PATCH 1/4] media: venus: hfi_parser: add check to avoid out of bound access

[Vikash Garodia <quic_vgarodia@quicinc.com>]

On 11/5/2024 7:25 PM, Dmitry Baryshkov wrote:
> On Tue, Nov 05, 2024 at 02:24:54PM +0530, Vikash Garodia wrote:
>> There is a possibility that init_codecs is invoked multiple times during
>> manipulated payload from video firmware. In such case, if codecs_count
>> can get incremented to value more than MAX_CODEC_NUM, there can be OOB
>> access. Keep a check for max accessible memory before accessing it.
> 
> No. Please make sure that init_codecs() does a correct thing, so that
> core->codecs_count isn't incremented that much (or even better that
> init_codecs() doesn't do anything if it is executed second time).
init_codecs() parses the payload received from firmware and . I don't think we
can control this part when we have something like this from a malicious firmware
payload
HFI_PROPERTY_PARAM_CODEC_SUPPORTED
HFI_PROPERTY_PARAM_CODEC_SUPPORTED
HFI_PROPERTY_PARAM_CODEC_SUPPORTED
...
Limiting it to second iteration would restrict the functionality when property
HFI_PROPERTY_PARAM_CODEC_SUPPORTED is sent for supported number of codecs.

Regards,
Vikash
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 1a73374a04e5 ("media: venus: hfi_parser: add common capability parser")
>> Signed-off-by: Vikash Garodia <quic_vgarodia@quicinc.com>
>> ---
>>  drivers/media/platform/qcom/venus/hfi_parser.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/media/platform/qcom/venus/hfi_parser.c b/drivers/media/platform/qcom/venus/hfi_parser.c
>> index 3df241dc3a118bcdeb2c28a6ffdb907b644d5653..27d0172294d5154f4839e8cef172f9a619dfa305 100644
>> --- a/drivers/media/platform/qcom/venus/hfi_parser.c
>> +++ b/drivers/media/platform/qcom/venus/hfi_parser.c
>> @@ -23,6 +23,8 @@ static void init_codecs(struct venus_core *core)
>>  		return;
>>  
>>  	for_each_set_bit(bit, &core->dec_codecs, MAX_CODEC_NUM) {
>> +		if (core->codecs_count >= MAX_CODEC_NUM)
>> +			return;
>>  		cap = &caps[core->codecs_count++];
>>  		cap->codec = BIT(bit);
>>  		cap->domain = VIDC_SESSION_TYPE_DEC;
>> @@ -30,6 +32,8 @@ static void init_codecs(struct venus_core *core)
>>  	}
>>  
>>  	for_each_set_bit(bit, &core->enc_codecs, MAX_CODEC_NUM) {
>> +		if (core->codecs_count >= MAX_CODEC_NUM)
>> +			return;
>>  		cap = &caps[core->codecs_count++];
>>  		cap->codec = BIT(bit);
>>  		cap->domain = VIDC_SESSION_TYPE_ENC;
>>
>> -- 
>> 2.34.1
>>
>