Bug#993145: qemu-system-x86_64: ../../util/qemu-sockets.c:1348: socket_sockaddr_to_address_unix: Assertion `salen >= sizeof(su->sun_family) + 1 && salen <= sizeof(struct sockaddr_un)' failed.

[Michael Tokarev]

Alternatively, a debugging backtrace from the failing run will be
much apprecated, -- the `bt' gdb command after installing
qemu-system-x86's dbgsym package.
Thanks!