[PATCH v2 5/5] gpu: nova-core: use checked arithmetic in RISC-V firmware parsing

[Joel Fernandes]

Use checked_add() when computing offsets from firmware-provided values
in the RISC-V firmware parsing code. These values come from the BinHdr
structure parsed from the firmware file header.

Reviewed-by: Zhi Wang <zhiw at nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf at nvidia.com>
---
 drivers/gpu/nova-core/firmware/riscv.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nova-core/firmware/riscv.rs b/drivers/gpu/nova-core/firmware/riscv.rs
index 28dfef63657a..97030bdd9991 100644
--- a/drivers/gpu/nova-core/firmware/riscv.rs
+++ b/drivers/gpu/nova-core/firmware/riscv.rs
@@ -47,10 +47,11 @@ impl RmRiscvUCodeDesc {
     /// Fails if the header pointed at by `bin_fw` is not within the bounds of the firmware image.
     fn new(bin_fw: &BinFirmware<'_>) -> Result<Self> {
         let offset = usize::from_safe_cast(bin_fw.hdr.header_offset);
+        let end = offset.checked_add(size_of::<Self>()).ok_or(EINVAL)?;
 
         bin_fw
             .fw
-            .get(offset..offset + size_of::<Self>())
+            .get(offset..end)
             .and_then(Self::from_bytes_copy)
             .ok_or(EINVAL)
     }
@@ -80,8 +81,9 @@ pub(crate) fn new(dev: &device::Device<device::Bound>, fw: &Firmware) -> Result<
         let ucode = {
             let start = usize::from_safe_cast(bin_fw.hdr.data_offset);
             let len = usize::from_safe_cast(bin_fw.hdr.data_size);
+            let end = start.checked_add(len).ok_or(EINVAL)?;
 
-            DmaObject::from_data(dev, fw.data().get(start..start + len).ok_or(EINVAL)?)?
+            DmaObject::from_data(dev, fw.data().get(start..end).ok_or(EINVAL)?)?
         };
 
         Ok(Self {
-- 
2.34.1