[PATCH v5 02/22] gpu: nova-core: vbios: use checked arithmetic for bios image range end

[Eliot Courtney]

`read_bios_image_at_offset` is called with a length from the VBIOS
header, so we should be more defensive here and use checked arithmetic.

Fixes: 6fda04e7f0cd ("gpu: nova-core: vbios: Add base support for VBIOS construction and iteration")
Reviewed-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Eliot Courtney <ecourtney@xxxxxxxxxx>
---
 drivers/gpu/nova-core/vbios.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
index 7bec81a37340..180928433766 100644
--- a/drivers/gpu/nova-core/vbios.rs
+++ b/drivers/gpu/nova-core/vbios.rs
@@ -238,8 +238,8 @@ fn read_bios_image_at_offset(
         len: usize,
         context: &str,
     ) -> Result<BiosImage> {
-        let data_len = self.data.len();
-        if offset + len > data_len {
+        let end = offset.checked_add(len).ok_or(EINVAL)?;
+        if end > self.data.len() {
             self.read_more_at_offset(offset, len).inspect_err(|e| {
                 dev_err!(
                     self.dev,
@@ -250,7 +250,7 @@ fn read_bios_image_at_offset(
             })?;
         }
 
-        BiosImage::new(self.dev, &self.data[offset..offset + len]).inspect_err(|err| {
+        BiosImage::new(self.dev, &self.data[offset..end]).inspect_err(|err| {
             dev_err!(
                 self.dev,
                 "Failed to {} at offset {:#x}: {:?}\n",

-- 
2.54.0