1 files changed, 26 insertions, 19 deletions
diff --git a/third_party/rust/wgpu-core/src/command/clear.rs b/third_party/rust/wgpu-core/src/command/clear.rs
index 2569fea1a4..e404fabb14 100644
--- a/third_party/rust/wgpu-core/src/command/clear.rs
+++ b/third_party/rust/wgpu-core/src/command/clear.rs
@@ -39,6 +39,11 @@ pub enum ClearError {
     UnalignedFillSize(BufferAddress),
     #[error("Buffer offset {0:?} is not a multiple of `COPY_BUFFER_ALIGNMENT`")]
     UnalignedBufferOffset(BufferAddress),
+    #[error("Clear starts at offset {start_offset} with size of {requested_size}, but these added together exceed `u64::MAX`")]
+    OffsetPlusSizeExceeds64BitBounds {
+        start_offset: BufferAddress,
+        requested_size: BufferAddress,
+    },
     #[error("Clear of {start_offset}..{end_offset} would end up overrunning the bounds of the buffer of size {buffer_size}")]
     BufferOverrun {
         start_offset: BufferAddress,
@@ -117,25 +122,27 @@ impl Global {
         if offset % wgt::COPY_BUFFER_ALIGNMENT != 0 {
             return Err(ClearError::UnalignedBufferOffset(offset));
         }
-        if let Some(size) = size {
-            if size % wgt::COPY_BUFFER_ALIGNMENT != 0 {
-                return Err(ClearError::UnalignedFillSize(size));
-            }
-            let destination_end_offset = offset + size;
-            if destination_end_offset > dst_buffer.size {
-                return Err(ClearError::BufferOverrun {
+
+        let size = size.unwrap_or(dst_buffer.size.saturating_sub(offset));
+        if size % wgt::COPY_BUFFER_ALIGNMENT != 0 {
+            return Err(ClearError::UnalignedFillSize(size));
+        }
+        let end_offset =
+            offset
+                .checked_add(size)
+                .ok_or(ClearError::OffsetPlusSizeExceeds64BitBounds {
                     start_offset: offset,
-                    end_offset: destination_end_offset,
-                    buffer_size: dst_buffer.size,
-                });
-            }
+                    requested_size: size,
+                })?;
+        if end_offset > dst_buffer.size {
+            return Err(ClearError::BufferOverrun {
+                start_offset: offset,
+                end_offset,
+                buffer_size: dst_buffer.size,
+            });
         }
 
-        let end = match size {
-            Some(size) => offset + size,
-            None => dst_buffer.size,
-        };
-        if offset == end {
+        if offset == end_offset {
             log::trace!("Ignoring fill_buffer of size 0");
             return Ok(());
         }
@@ -144,7 +151,7 @@ impl Global {
         cmd_buf_data.buffer_memory_init_actions.extend(
             dst_buffer.initialization_status.read().create_action(
                 &dst_buffer,
-                offset..end,
+                offset..end_offset,
                 MemoryInitKind::ImplicitlyInitialized,
             ),
         );
@@ -154,7 +161,7 @@ impl Global {
         let cmd_buf_raw = cmd_buf_data.encoder.open()?;
         unsafe {
             cmd_buf_raw.transition_buffers(dst_barrier.into_iter());
-            cmd_buf_raw.clear_buffer(dst_raw, offset..end);
+            cmd_buf_raw.clear_buffer(dst_raw, offset..end_offset);
         }
         Ok(())
     }
@@ -366,7 +373,7 @@ fn clear_texture_via_buffer_copies<A: HalApi>(
         assert!(
             max_rows_per_copy > 0,
             "Zero buffer size is too small to fill a single row \
-                 of a texture with format {:?} and desc {:?}",
+            of a texture with format {:?} and desc {:?}",
             texture_desc.format,
             texture_desc.size
         );