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)?;
 
                 self.fw
                     // Get signatures range.
-                    .get(
-                        signatures_start
-                            ..signatures_start + usize::from_safe_cast(self.hdr.sig_prod_size),
-                    )
+                    .get(signatures_start..signatures_end)
                     .ok_or(EINVAL)?
                     .chunks_exact(sig_size.into_safe_cast())
             }
-- 
2.34.1

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>

>                  self.fw
>                      // Get signatures range.
> -                    .get(
> -                        signatures_start
> -                            ..signatures_start +
> usize::from_safe_cast(self.hdr.sig_prod_size),
> -                    )
> +                    .get(signatures_start..signatures_end)
>                      .ok_or(EINVAL)?
>                      .chunks_exact(sig_size.into_safe_cast())
>              }

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