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[Bug 1815371] Re: SPICE session's connection_id's are not unique
From: |
Thomas Huth |
Subject: |
[Bug 1815371] Re: SPICE session's connection_id's are not unique |
Date: |
Wed, 05 May 2021 11:17:25 -0000 |
This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:
https://gitlab.com/qemu-project/qemu/-/issues/163
** Changed in: qemu
Status: New => Expired
** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #163
https://gitlab.com/qemu-project/qemu/-/issues/163
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https://bugs.launchpad.net/bugs/1815371
Title:
SPICE session's connection_id's are not unique
Status in QEMU:
Expired
Status in qemu package in Debian:
Confirmed
Bug description:
From: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=920897
=====
When creating a virtual machine with qemu (e.g. via libvirt) including
a SPICE server, the client_id of the SPICE session is not unique. For
example, starting multiple virtual machines on the same libvirtd, the
client_id is the same for all virtual machine's SPICE sessions.
A description of the client_id can be found in
https://www.spice-space.org/static/docs/spice_protocol.pdf under
section 2.11. c) :
"UINT32 connection_id - In case of a new session (i.e., channel type is
RED_CHANNEL_MAIN) this field is set to zero, and in response the server will
allocate session id and will send it via the RedLinkReply message. In case of
all other channel types, this field will be equal to the allocated session id"
The relevant code for generating client ids in libspice-server1 can be found
here:
https://gitlab.freedesktop.org/spice/spice/blob/v0.12.8/server/reds.c#L1614
This uses rand() to generate the random id, but qemu (at least in the
case of qemu-system-x86) fails to initialize the RNG seed (with e.g.
srand()).
The result is, that every SPICE session started (by e.g. libvirtd) has the
same client_id. Usually, this is not a problem, but running something like a
SPICE proxy, relying on the client_id to correctly route connections, this
creates problems.
Adding something like 'srand(time(NULL));' to qemu (in vl.c) solves this
issue. Related (as seen in some VNC patches, e.g.
'CVE-2017-15124/04-ui-avoid-pointless-VNC-updates-if-framebuffer-isn-t-.patch/ui/vnc.c'
): srand(time(NULL)+getpid()+getpid()*987654+rand());
Tested on Debian 9.7 with kernel 4.9.0-6-amd64 #1 SMP Debian 4.9.88-1+deb9u1
(2018-05-07) x86_64 GNU/Linux.
=====
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