Yes, it's fixed in v4.2.0, and with the help of your test program I've bisect to the fix:
commit 1645fb5a1e537f85eda744bfa6e9d3dda047ba28 Author: Shu-Chun Weng <s...@google.com> Date: Thu Oct 17 17:19:20 2019 -0700 Fix unsigned integer underflow in fd-trans.c In any of these `*_for_each_*` functions, the last entry in the buffer (so the "remaining length in the buffer" `len` is equal to the length of the entry `nlmsg_len`/`nla_len`/etc) has size that is not a multiple of the alignment, the aligned lengths `*_ALIGN(*_len)` will be greater than `len`. Since `len` is unsigned (`size_t`), it underflows and the loop will read pass the buffer. This may manifest as random EINVAL or EOPNOTSUPP error on IO or network system calls. Signed-off-by: Shu-Chun Weng <s...@google.com> Reviewed-by: Laurent Vivier <laur...@vivier.eu> Message-Id: <20191018001920.178283-1-...@google.com> Signed-off-by: Laurent Vivier <laur...@vivier.eu> ** Changed in: qemu Status: New => Fix Released -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1857811 Title: qemu user static binary seems to lack support for network namespace. Status in QEMU: Fix Released Bug description: Whenever I execute emerge in gentoo linux in qemu-aarch64 chroot, I see the following error message. Unable to configure loopback interface: Operation not supported If I disable emerge's network-sandbox which utilizes network namespace, the error disappears. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1857811/+subscriptions