[Qemu-devel] [PATCH 3/3] virtio-blk: Treat read/write beyond end as invalid

[Markus Armbruster <armbru@redhat.com>]

The block layer fails such reads and writes just fine.  However, they
then get treated like valid operations that fail: the error action
gets executed.  Unwanted; reporting the error to the guest is the only
sensible action.

Reject them before passing them to the block layer.  This bypasses the
error action and I/O accounting.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 hw/block/virtio-blk.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 2c68d0d..0b38049 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -284,12 +284,19 @@ static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb)
 static bool virtio_blk_sect_range_ok(VirtIOBlock *dev,
                                      uint64_t sector, size_t size)
 {
+    uint64_t nb_sectors = size >> BDRV_SECTOR_BITS;
+    uint64_t total_sectors;
+
     if (sector & dev->sector_mask) {
         return false;
     }
     if (size % dev->conf->logical_block_size) {
         return false;
     }
+    bdrv_get_geometry(dev->bs, &total_sectors);
+    if (sector > total_sectors || nb_sectors > total_sectors - sector) {
+        return false;
+    }
     return true;
 }
 
-- 
1.9.3