[Qemu-devel] qemu 1.2 segfault on shutdown (ioh->deleted == false, io->fd == -1)

["Richard W.M. Jones" <rjones@redhat.com>]

I'm tracking this bug here:
https://bugzilla.redhat.com/show_bug.cgi?id=853408

Does anyone recognize this segfault on shutdown when using either a
console or a virtio-serial char device?

It's only caught in Fedora because we compile with 'fortify source' so
the attempt to modify a negative offset in an fdset is caught.
Probably it just overwrites a random bit of memory for everyone else.

(gdb) frame 6
#6  0x00007f173d3d373d in qemu_iohandler_poll (readfds=readfds@entry=
    0x7f173dd97b60 <rfds>, writefds=writefds@entry=0x7f173dd97be0 <wfds>, 
    xfds=xfds@entry=0x7f173dd97c60 <xfds>, ret=ret@entry=1) at iohandler.c:156
156             if (!ioh->deleted && ioh->fd_read && FD_ISSET(ioh->fd, readfds)) {
(gdb) print *ioh
$1 = {
  fd_read_poll = 0x7f173d49a7f0 <tcp_chr_read_poll>, 
  fd_read = 0x7f173d49be30 <tcp_chr_read>, 
  fd_write = 0x0, 
  opaque = 0x7f173fe3a380, 
  next = {
    le_next = 0x7f1728003310, 
    le_prev = 0x7f173dd96a70 <io_handlers>
  }, 
  fd = -1, 
  deleted = false
}

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top