Re: [PATCH v1] soc: qcom: mdt_loader: Add Upperbounds check for program header access

[Auditya Bhattaram <quic_audityab@quicinc.com>]

On 2/2/2024 1:34 PM, Mukesh Ojha wrote:
> 
> This should be v2., first time patches is always counted as v1
> 
> On 2/2/2024 12:09 PM, Auditya Bhattaram wrote:
>> hash_index is evaluated by looping phdrs till QCOM_MDT_TYPE_HASH
>> is found. Add an upperbound check to phdrs to access within elf size.
>>
>> Signed-off-by: Auditya Bhattaram <quic_audityab@quicinc.com> > ---
>> Added error prints for Invalid access.
>> Link for previous discussion 
>> https://lore.kernel.org/linux-arm-msm/5d7a3b97-d840-4863-91a0-32c1d8e7532f@linaro.org/T/#t
> 
> Would be better if you take reference from other patches,
> 
> Like above can be done as,
> 
> Changes in v2:
>    -  ...
>    -  ,,,
>> ---
>>   drivers/soc/qcom/mdt_loader.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/soc/qcom/mdt_loader.c 
>> b/drivers/soc/qcom/mdt_loader.c
>> index 6f177e46fa0f..61e2377cc5c3 100644
>> --- a/drivers/soc/qcom/mdt_loader.c
>> +++ b/drivers/soc/qcom/mdt_loader.c
>> @@ -145,6 +145,11 @@ void *qcom_mdt_read_metadata(const struct 
>> firmware *fw, size_t *data_len,
>>       if (phdrs[0].p_type == PT_LOAD)
>>           return ERR_PTR(-EINVAL);
>>
>> +    if (((size_t)(phdrs + ehdr->e_phnum)) > ((size_t)ehdr + fw->size)) {
>> +        dev_err(dev, "Invalid phdrs access: %s\n", fw_name);
>> +        return ERR_PTR(-EINVAL);
>> +    }
>> +
> 
> Should this not be marked for stable kernel ? as without this it could 
> be accessing beyond fw_size for uncertain scenario.
> 
> -Mukesh

Yes This should be marked for stable.

> 
>>       for (i = 1; i < ehdr->e_phnum; i++) {
>>           if ((phdrs[i].p_flags & QCOM_MDT_TYPE_MASK) == 
>> QCOM_MDT_TYPE_HASH) {
>>               hash_segment = i;
>> -- 
>> 2.17.1
>>
>>