Re: [PATCH 2/5] gpu: nova-core: vbios: limit `BitToken` entry reads

Joel Fernandes
2026-04-10T14:30:24Z

On 4/10/2026 4:38 AM, Eliot Courtney wrote:
> If `header.token_size` is smaller than `BitToken`, then we currently can
> read past the end of `image.base.data`. Check that the token size is at
> least as big as `BitToken`.
>
> Fixes: dc70c6ae2441 ("gpu: nova-core: vbios: Add support to look up PMU table in FWSEC")
> Signed-off-by: Eliot Courtney <ecourtney@nvidia.com>
> ---
> drivers/gpu/nova-core/vbios.rs | 34 +++++++++++++++++-----------------
> 1 file changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
> index 6de7e58e0da0..de856000de23 100644
> --- a/drivers/gpu/nova-core/vbios.rs
> +++ b/drivers/gpu/nova-core/vbios.rs
> @@ -423,31 +423,31 @@ impl BitToken {
> /// Find a BIT token entry by BIT ID in a PciAtBiosImage
> fn from_id(image: &PciAtBiosImage, token_id: u8) -> Result<Self> {
> let header = &image.bit_header;
> + let entry_size = usize::from(header.token_size);
> +
> + if entry_size < size_of::<BitToken>() {
> + return Err(EINVAL);
> + }
>
> // Offset to the first token entry
> let tokens_start = image.bit_offset + usize::from(header.header_size);
>
> for i in 0..usize::from(header.token_entries) {
> - let entry_offset = tokens_start + (i * usize::from(header.token_size));
> -
> - // Make sure we don't go out of bounds
> - if entry_offset + usize::from(header.token_size) > image.base.data.len() {
> - return Err(EINVAL);
> - }
> + let entry_offset = tokens_start + (i * entry_size);
> + let entry = image
> + .base
> + .data
> + .get(entry_offset..)
> + .and_then(|data| data.get(..entry_size))
> + .ok_or(EINVAL)?;
>
> // Check if this token has the requested ID
> - if image.base.data[entry_offset] == token_id {
> + if entry[0] == token_id {
> return Ok(BitToken {
> - id: image.base.data[entry_offset],
> - data_version: image.base.data[entry_offset + 1],
> - data_size: u16::from_le_bytes([
> - image.base.data[entry_offset + 2],
> - image.base.data[entry_offset + 3],
> - ]),
> - data_offset: u16::from_le_bytes([
> - image.base.data[entry_offset + 4],
> - image.base.data[entry_offset + 5],
> - ]),
> + id: entry[0],
> + data_version: entry[1],
> + data_size: u16::from_le_bytes([entry[2], entry[3]]),
> + data_offset: u16::from_le_bytes([entry[4], entry[5]]),
> });
> }
> }
>

Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>

thanks,

--
Joel Fernandes