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

[Bryan O'Donoghue <bryan.odonoghue@linaro.org>]

On 05/11/2024 08:54, 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.
> 
> 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;
> 

I don't see how codecs_count could be greater than the control, since 
you increment by one on each loop but >= is fine too I suppose.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>