block/export: port virtio-blk read/write range check

Check that the sector number and byte count are valid.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210223144653.811468-13-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block/export/vhost-user-blk-server.c

@@ -209,6 +209,8 @@ static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
     switch (type & ~VIRTIO_BLK_T_BARRIER) {
     case VIRTIO_BLK_T_IN:
     case VIRTIO_BLK_T_OUT: {
+        QEMUIOVector qiov;
+        int64_t offset;
         ssize_t ret = 0;
         bool is_write = type & VIRTIO_BLK_T_OUT;
         req->sector_num = le64_to_cpu(req->out.sector);
@@ -218,13 +220,24 @@ static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
             break;
         }
 
-        int64_t offset = req->sector_num << VIRTIO_BLK_SECTOR_BITS;
-        QEMUIOVector qiov;
         if (is_write) {
             qemu_iovec_init_external(&qiov, out_iov, out_num);
-            ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0);
         } else {
             qemu_iovec_init_external(&qiov, in_iov, in_num);
+        }
+
+        if (unlikely(!vu_blk_sect_range_ok(vexp,
+                                           req->sector_num,
+                                           qiov.size))) {
+            req->in->status = VIRTIO_BLK_S_IOERR;
+            break;
+        }
+
+        offset = req->sector_num << VIRTIO_BLK_SECTOR_BITS;
+
+        if (is_write) {
+            ret = blk_co_pwritev(blk, offset, qiov.size, &qiov, 0);
+        } else {
             ret = blk_co_preadv(blk, offset, qiov.size, &qiov, 0);
         }
         if (ret >= 0) {