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

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Message-ID: <647a32b9-94e4-ce9d-ed9a-771d32fe7784@quicinc.com>
Date: Thu, 7 Nov 2024 13:54:13 +0530
From: Vikash Garodia <quic_vgarodia@...cinc.com>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        Stanimir Varbanov
	<stanimir.k.varbanov@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
CC: <linux-media@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH 1/4] media: venus: hfi_parser: add check to avoid out of
 bound access


On 11/6/2024 3:53 PM, Bryan O'Donoghue wrote:
> On 06/11/2024 07:25, Vikash Garodia wrote:
>>>>            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.
>> Assume the payload from malicious firmware is packed like below
>> HFI_PROPERTY_PARAM_CODEC_SUPPORTED
>> HFI_PROPERTY_PARAM_CODEC_SUPPORTED
>> HFI_PROPERTY_PARAM_CODEC_SUPPORTED
>> .....
>> for 32 or more instances of above type
> 
> But you do this
> 
>           cap = &caps[core->codecs_count++];
> 
> for each bit.
Yes. Let say that packet is written more than 32 times in the payload response
from bad firmware and each has 1 bit set. core->codecs_count would be
incremented beyond the allocated space.

Regards,
Vikash

> 
> Anyway consider Dmitry's input re only calling this function once instead.
> 
> ---
> bod