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

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Message-ID: <8d930ac7-11b1-437b-be18-7a785f20a72f@gmail.com>
Date: Sun, 25 Jan 2026 10:09:19 +0100
From: Dirk Behme <dirk.behme@...il.com>
To: Joel Fernandes <joelagnelf@...dia.com>, linux-kernel@...r.kernel.org,
 Danilo Krummrich <dakr@...nel.org>, Alexandre Courbot <acourbot@...dia.com>,
 Alice Ryhl <aliceryhl@...gle.com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Cc: John Hubbard <jhubbard@...dia.com>, Alistair Popple <apopple@...dia.com>,
 Timur Tabi <ttabi@...dia.com>, Edwin Peer <epeer@...dia.com>,
 Zhi Wang <zhiw@...dia.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
 Björn Roy Baron <bjorn3_gh@...tonmail.com>,
 Benno Lossin <lossin@...nel.org>, Andreas Hindborg <a.hindborg@...nel.org>,
 Trevor Gross <tmgross@...ch.edu>, nouveau@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v1 1/5] gpu: nova-core: use checked arithmetic in FWSEC
 firmware parsing

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@...dia.com>
> ---
>  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.

Best regards

Dirk