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Bug 2111524 - Remote TLS connections sometimes fail with nbd_pread: nothing to poll for in state REPLY.START: Invalid argument
Summary: Remote TLS connections sometimes fail with nbd_pread: nothing to poll for in ...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: libnbd
Version: 9.1
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Richard W.M. Jones
QA Contact: Vera
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2022-07-27 12:29 UTC by Richard W.M. Jones
Modified: 2022-11-15 10:07 UTC (History)
8 users (show)

Fixed In Version: libnbd-1.12.6-1.el9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2022-11-15 09:50:16 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)
make-pki.sh (1.68 KB, application/x-shellscript)
2022-07-27 12:31 UTC, Richard W.M. Jones 		no flags Details
test-read.py (247 bytes, text/x-python3)
2022-07-27 12:34 UTC, Richard W.M. Jones 		no flags Details
make-pki.sh (1.78 KB, application/x-shellscript)
2022-08-04 10:55 UTC, Richard W.M. Jones 		no flags Details
Show Obsolete (1) View All


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-129279 0 None None None 2022-07-27 12:37:30 UTC
Red Hat Product Errata RHBA-2022:7944 0 None None None 2022-11-15 09:50:21 UTC

Description Richard W.M. Jones 2022-07-27 12:29:14 UTC 
Description of problem:

Upstream a strange bug was reported when libnbd connects to a
remote server over TLS and tries to read.  The error happens
randomly but is reproducible if you run the test many times.

We have identified the problem and fixed it upstream.

Version-Release number of selected component (if applicable):

libnbd-1.12.5-1.el9

How reproducible:

Quite rare.

Steps to Reproduce:

1. Set up X.509 certificates using the "make-pki.sh" script attached.
I created certificates in /var/tmp/pki/.

2. Take a random qcow2 file, eg. a virtual machine disk image.
I'm using a Fedora cloud image.

3. Run qemu-nbd on the server, enabling TLS:

$ qemu-nbd -t -f qcow2 Fedora-Cloud-Base-35-1.2.x86_64.qcow2  --object tls-creds-x509,id=tls0,endpoint=server,dir=/var/tmp/pki,verify-peer=false --tls-creds tls0

4. Copy /var/tmp/pki to another machine.

5. On the second machine run the second attached test program.

/var/tmp/test-read.py

6. It should eventually fail with:

nbd_pread: nothing to poll for in state REPLY.START: Invalid argument
Comment 1 Richard W.M. Jones 2022-07-27 12:31:24 UTC 
Created attachment 1899642 [details]
make-pki.sh

NB: You need to adjust the SERVER=... in the script!
Comment 2 Richard W.M. Jones 2022-07-27 12:34:39 UTC 
Created attachment 1899643 [details]
test-read.py

Note: You need to adjust the server name in the script.
Comment 3 Richard W.M. Jones 2022-07-27 12:35:25 UTC 
You may also have to open port 10809 on the server's firewall.
Comment 4 Richard W.M. Jones 2022-07-27 12:36:30 UTC 
Upstream fix:
https://gitlab.com/nbdkit/libnbd/-/commit/39afa21c22ef2c49f9e039e4c7014c9261e65755
Comment 5 Richard W.M. Jones 2022-07-28 10:32:42 UTC 
I bumped the version to 1.12.6, but this isn't really a rebase, it's
a move along the stable branch bringing in only small bug fixes:

https://gitlab.com/nbdkit/libnbd/-/commits/rhel-9.1/
Comment 8 Richard W.M. Jones 2022-08-04 10:55:37 UTC 
Created attachment 1903530 [details]
make-pki.sh

This is a slightly modified make-pki.sh which sets the cn, dns_name
and ip_address fields of the server certificate.
Comment 9 Vera 2022-08-05 03:05:01 UTC 
Reproduce with 
qemu-img-7.0.0-9.el9.x86_64
libnbd-1.12.5-1.el9.x86_64

Steps to Reproduce:
1. Set up a qemu-nbd + TLS server using steps 1.-4

2. On the client machine run the test program.(client and server should be in bad network.Using "tc" to make pkt loss and corruption.)

# tc qdisc add dev enp0s31f6 root netem loss 30%
# ./test-read.py 
...................................................................Traceback (most recent call last):
  File "/home/pki/./test-read.py", line 11, in <module>
    h.pread(4*1024*1024, 1024)
  File "/usr/lib64/python3.9/site-packages/nbd.py", line 1595, in pread
    return libnbdmod.pread(self._o, count, offset, flags)
nbd.Error: nbd_pread: nothing to poll for in state REPLY.START: Invalid argument (EINVAL)


Verified with 
qemu-img-7.0.0-9.el9.x86_64
libnbd-1.12.6-1.el9.x86_64

Steps:
1. Set up a qemu-nbd + TLS server using steps 1.-4

2. On the client machine run the test program.

# ./test-read.py 
.............................................
(As expected dotting)

Mark Verified:Tested. Moving to VERIFIED.
Comment 11 errata-xmlrpc 2022-11-15 09:50:16 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (libnbd bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:7944
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