[Qemu-devel] [Bug 1823790] Re: QEMU mishandling of SO_PEERSEC forces systemd into tight loop

[Peter Maydell]

As described on the systemd issue, the syscall we're getting wrong here
is getsockopt(fd, SOL_SOCKET, SO_PEERSEC, ...). Our linux-
user/syscall.c:do_getsockopt() doesn't have any special case code for
the payload on this function, so we treat it as if it were just an
integer payload, which is not correct here.

Unfortunately I can't find any documentation on exactly what SO_PEERSEC
does or what the payload format is, which makes it pretty hard to fix
this bug :-( It's not listed in the socket(7) manpage --
https://linux.die.net/man/7/socket -- which is where I'd expect to find
it, and the kernel source code is pretty confusing in this area.


** Summary changed:

- QEMU forces systemd into tight loop
+ QEMU mishandling of SO_PEERSEC forces systemd into tight loop

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https://bugs.launchpad.net/bugs/1823790

Title:
  QEMU mishandling of SO_PEERSEC forces systemd into tight loop

Status in QEMU:
  New

Bug description:
  While building Debian images for embedded ARM target systems I
  detected that QEMU seems to force newer systemd daemons into a tight
  loop.

  My setup is the following:

  Host machine: Ubuntu 18.04, amd64
  LXD container: Debian Buster, arm64, systemd 241
  QEMU: qemu-aarch64-static, 4.0.0-rc2 (custom build) and 3.1.0 (Debian 
1:3.1+dfsg-7)

  To easily reproduce the issue I have created the following repository:
  https://github.com/lueschem/edi-qemu

  The call where systemd gets looping is the following:
  2837 getsockopt(3,1,31,274891889456,274887218756,274888927920) = -1 errno=34 
(Numerical result out of range)

  Furthermore I also verified that the issue is not related to LXD.
  The same behavior can be reproduced using systemd-nspawn.

  This issue reported against systemd seems to be related:
  https://github.com/systemd/systemd/issues/11557

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