In qemu 4.2, I accidentally introduced the ability for an NBD client
obeying the specification to kill qemu as NBD server with an assertion
failure when the client requests an unusually long export name, as a
regression from the intended graceful server error message back to the
client.  Given that the DoS security hole can be mitigated by
requiring TLS (and a client with TLS credentials is less likely to
play such games), the plan is to make the issue public today and send
a pull request through my NBD tree on Tuesday.

We may still want to revisit whether the block layer caps display
names to 4095 bytes, or whether it should track a malloc'd name even
when that name exceeds 4k.

Eric Blake (2):
  nbd/server: Avoid long error message assertions CVE-2020-10761
  block: Call attention to truncation of long NBD exports

 block.c                    |  7 +++++--
 block/nbd.c                | 21 +++++++++++++--------
 nbd/server.c               | 28 +++++++++++++++++++++++++---
 tests/qemu-iotests/143     |  4 ++++
 tests/qemu-iotests/143.out |  2 ++
 5 files changed, 49 insertions(+), 13 deletions(-)

-- 
2.27.0