block/iscsi: check for oversized requests

Cancel oversized requests early. They would generate
an iSCSI protocol error anyway; after having transferred
possibly a lot of data over the wire.

Suggested-By: Max Reitz <mreitz@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/block/iscsi.c b/block/iscsi.c
index a4ba33b..111065d 100644 (file)
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -362,6 +362,12 @@ static int coroutine_fn iscsi_co_writev(BlockDriverState *bs,
         return -EINVAL;
     }
 
+    if (bs->bl.max_transfer_length && nb_sectors > bs->bl.max_transfer_length) {
+        error_report("iSCSI Error: Write of %d sectors exceeds max_xfer_len "
+                     "of %d sectors", nb_sectors, bs->bl.max_transfer_length);
+        return -EINVAL;
+    }
+
     lba = sector_qemu2lun(sector_num, iscsilun);
     num_sectors = sector_qemu2lun(nb_sectors, iscsilun);
     iscsi_co_init_iscsitask(iscsilun, &iTask);
@@ -529,6 +535,12 @@ static int coroutine_fn iscsi_co_readv(BlockDriverState *bs,
         return -EINVAL;
     }
 
+    if (bs->bl.max_transfer_length && nb_sectors > bs->bl.max_transfer_length) {
+        error_report("iSCSI Error: Read of %d sectors exceeds max_xfer_len "
+                     "of %d sectors", nb_sectors, bs->bl.max_transfer_length);
+        return -EINVAL;
+    }
+
     if (iscsilun->lbprz && nb_sectors >= ISCSI_CHECKALLOC_THRES &&
         !iscsi_allocationmap_is_allocated(iscsilun, sector_num, nb_sectors)) {
         int64_t ret;