From 1ba5f15198cfe90f5bf00e77d9af06cd371df842 Mon Sep 17 00:00:00 2001
From: Rob Bradford <rbradford@meta.com>
Date: Wed, 8 Jul 2026 15:32:30 +0100
Subject: [PATCH] block: Check request total length is a multiple of
 SECTOR_SIZE

The request can be spread over multiple descriptors but the virtio-block
specification (and this code) expects that is a whole number of sectors
(512 bytes).

Signed-off-by: Rob Bradford <rbradford@meta.com>
---
 block/src/io/request.rs | 5 ++++-
 block/src/lib.rs        | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/src/io/request.rs b/block/src/io/request.rs
index a6cdf4d7b..bd78fff91 100644
--- a/block/src/io/request.rs
+++ b/block/src/io/request.rs
@@ -644,7 +644,10 @@ impl Request {
         if total_bytes == 0 {
             return Ok(());
         }
-        let total_sectors = total_bytes.div_ceil(SECTOR_SIZE);
+        if !total_bytes.is_multiple_of(SECTOR_SIZE) {
+            return Err(ExecuteError::BadRequest(Error::InvalidDataLength));
+        }
+        let total_sectors = total_bytes / SECTOR_SIZE;
         let end_sector = self
             .sector
             .checked_add(total_sectors)
diff --git a/block/src/lib.rs b/block/src/lib.rs
index d8c5600b8..903531660 100644
--- a/block/src/lib.rs
+++ b/block/src/lib.rs
@@ -71,6 +71,8 @@ pub enum Error {
     GetFileMetadata(#[source] io::Error),
     #[error("The requested operation would cause a seek beyond disk end")]
     InvalidOffset,
+    #[error("Request data length is not a multiple of the 512-byte sector size")]
+    InvalidDataLength,
     #[error("Failure in qcow")]
     QcowError(#[source] qcow::Error),
     #[error("The requested operation does not support multiple descriptors")]