Re: [PATCH v1 2/5] gpu: nova-core: use checked arithmetic in Booter signature parsing

[Joel Fernandes <joelagnelf@nvidia.com>]

On 1/26/2026 3:08 AM, Zhi Wang wrote:
> On Sat, 24 Jan 2026 18:18:27 -0500
> Joel Fernandes <joelagnelf@nvidia.com> wrote:
> 
>> Use checked_add() when computing signature offsets from firmware-
>> provided values in signatures_iter().
>>
>> Without checked arithmetic, overflow could wrap to a small plausible
>> offset that points to entirely wrong data.
>>
>> Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
>> ---
>>   drivers/gpu/nova-core/firmware/booter.rs | 19 ++++++++++++++-----
>>   1 file changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/nova-core/firmware/booter.rs
>> b/drivers/gpu/nova-core/firmware/booter.rs index
>> 86556cee8e67..f5ad619dc055 100644 ---
>> a/drivers/gpu/nova-core/firmware/booter.rs +++
>> b/drivers/gpu/nova-core/firmware/booter.rs @@ -119,14 +119,23 @@ fn
>> signatures_iter(&'a self) -> Result<impl Iterator<Item =
>> BooterSignature<'a>> Some(sig_size) => { let patch_sig =
>>                       frombytes_at::<u32>(self.fw,
>> self.hdr.patch_sig_offset.into_safe_cast())?;
>> -                let signatures_start =
>> usize::from_safe_cast(self.hdr.sig_prod_offset + patch_sig); +
>> +                // Compute signatures_start = hdr.sig_prod_offset +
>> patch_sig.
>> +                let signatures_start = self
>> +                    .hdr
>> +                    .sig_prod_offset
>> +                    .checked_add(patch_sig)
>> +                    .map(usize::from_safe_cast)
>> +                    .ok_or(EINVAL)?;
>> +
>> +                // Compute signatures_end = signatures_start +
>> hdr.sig_prod_size.
>> +                let signatures_end = signatures_start
>> +
>> .checked_add(usize::from_safe_cast(self.hdr.sig_prod_size))
>> +                    .ok_or(EINVAL)?;
>>   
> 
> The same concern of comment format in PATCH 1 raised by Dirk, With that
> addressed,
> 
> Reviewed-by: Zhi Wang <zhiw@nvidia.com>
Fixed and applied your tags, thank you!

--
Joel Fernandes