Re: [PATCH v1 1/5] gpu: nova-core: use checked arithmetic in FWSEC firmware parsing

[Joel Fernandes]

On Jan 25, 2026, at 4:09 AM, Dirk Behme <dirk.behme@xxxxxxxxx> wrote:
>
> Hi Joel,
>
> On 25.01.26 00:18, Joel Fernandes wrote:
>> Use checked_add() and checked_mul() when computing offsets from
>> firmware-provided values in new_fwsec().
>>
>> Without checked arithmetic, corrupt firmware could cause integer overflow. The
>> danger is not just wrapping to a huge value, but potentially wrapping to a
>> small plausible offset that passes validation yet accesses entirely wrong data,
>> causing silent corruption or security issues.
>>
>> Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
>> ---
>> drivers/gpu/nova-core/firmware/fwsec.rs | 60 ++++++++++++++-----------
>> 1 file changed, 35 insertions(+), 25 deletions(-)
>>
>> diff --git a/drivers/gpu/nova-core/firmware/fwsec.rs b/drivers/gpu/nova-core/firmware/fwsec.rs
>> index a8ec08a500ac..1a91bbbce3d5 100644
>> --- a/drivers/gpu/nova-core/firmware/fwsec.rs
>> +++ b/drivers/gpu/nova-core/firmware/fwsec.rs
>> @@ -46,10 +46,7 @@
> ...
>> @@ -356,8 +362,12 @@ pub(crate) fn new(
>>         // Patch signature if needed.
>>         let desc = bios.fwsec_image().header()?;
>>         let ucode_signed = if desc.signature_count() != 0 {
>> -            let sig_base_img =
>> -                usize::from_safe_cast(desc.imem_load_size() + desc.pkc_data_offset());
>> +            // Compute sig_base_img = desc.imem_load_size + desc.pkc_data_offset.
>
> Nit: Drop `desc.` to make it consistent with the other comments.

Ok, thanks. I request anyone applying the patch to fix that on apply, but I can
totally do that if respinning/resending.

-- 
Joel Fernandes