[Libguestfs] [v2v PATCH 1/2] lib/utils: get_disk_allocated: assert that NBD block length is positive
It makes no sense for the NBD server to return a zero-length block, plus
it used to be a bug in the libnbd OCaml bindings to wrap 32-bit block
lengths with the MSB set around to negative (signed) 32-bit integers
(which would then be widened to negative (signed) 64-bit integers).
Any non-positive "len" value breaks the progression of
"fetch_offset",
potentially leading to an infinite loop.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2027598
Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
---
lib/utils.ml | 1 +
1 file changed, 1 insertion(+)
diff --git a/lib/utils.ml b/lib/utils.ml
index 4c43a4b5161d..f599b0e32450 100644
--- a/lib/utils.ml
+++ b/lib/utils.ml
@@ -197,6 +197,7 @@ let get_disk_allocated ~dir ~disknr =
for i = 0 to Array.length entries / 2 - 1 do
let len = Int64.of_int32 entries.(i * 2)
and typ = entries.(i * 2 + 1) in
+ assert (len > 0_L);
if Int32.logand typ 1_l = 0_l then
allocated := !allocated +^ len;
fetch_offset := !fetch_offset +^ len
--
2.19.1.3.g30247aa5d201