Description of problem:
Spice server aborts when spice client is connected while using by a user. I haven't observed any specific reproducer, I have a suspect It's related to arbitrary resolution change but I hit the bug even when typing in gnome terminal on the guest. 

QEMU stdout:
((null):15058): SpiceWorker-CRITICAL **: red_worker.c:5467:lz_usr_error: stride != width*bytes_per_pixel (rgb) 12 != 10 * 1 (11)

or

((null):15058): SpiceWorker-CRITICAL **: red_worker.c:5467:lz_usr_error: stride != width*bytes_per_pixel (rgb) 412 != 410 * 1 (11)


BT:
(gdb) thread apply all bt

Thread 7 (Thread 0x7fcb0dffa700 (LWP 15136)):
#0  pthread_cond_timedwait@@GLIBC_2.3.2 ()
    at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:216
#1  0x00007fcb664524b7 in cond_timedwait (unused=<value optimized out>)
    at posix-aio-compat.c:102
#2  aio_thread (unused=<value optimized out>) at posix-aio-compat.c:329
#3  0x00007fcb65d6d851 in start_thread (arg=0x7fcb0dffa700)
    at pthread_create.c:301
#4  0x00007fcb63e2c90d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 4 (Thread 0x7fcb5d2dd700 (LWP 15082)):
#0  0x00007fcb63e24a47 in ioctl () at ../sysdeps/unix/syscall-template.S:82
#1  0x00007fcb6643637a in kvm_run (env=0x7fcb679ce0b0)
    at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:1015
#2  0x00007fcb66436829 in kvm_cpu_exec (env=<value optimized out>)
    at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:1743
#3  0x00007fcb6643770d in kvm_main_loop_cpu (_env=0x7fcb679ce0b0)
    at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2004
#4  ap_main_loop (_env=0x7fcb679ce0b0)
    at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2060
#5  0x00007fcb65d6d851 in start_thread (arg=0x7fcb5d2dd700)
    at pthread_create.c:301
#6  0x00007fcb63e2c90d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 3 (Thread 0x7fcb0e9fb700 (LWP 15083)):
#0  0x00007fcb63d768a5 in raise (sig=6)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1  0x00007fcb63d78085 in abort () at abort.c:92
#2  0x00007fcb645d0c35 in spice_logv (log_domain=0x7fcb6464cd9c "SpiceWorker", 
    log_level=SPICE_LOG_LEVEL_CRITICAL, 
    strloc=0x7fcb6464d159 "red_worker.c:5467", 
    function=0x7fcb6464eeae "lz_usr_error", format=0x7fcb6465918a "%s", 
    args=0x7fcb0e9fa490) at log.c:109
#3  0x00007fcb645d0d6a in spice_log (log_domain=<value optimized out>, 
    log_level=<value optimized out>, strloc=<value optimized out>, 
    function=<value optimized out>, format=<value optimized out>) at log.c:123
#4  0x00007fcb645956d4 in lz_usr_error (usr=0x7fcb081d7720, 
    fmt=<value optimized out>) at red_worker.c:5467
#5  0x00007fcb645d5aae in lz_encode (lz=0x7fcb66361010, type=LZ_IMAGE_TYPE_A8, 
    width=10, height=9, top_down=1, lines=0x0, num_lines=0, stride=12, 
    io_ptr=0x7fcb09a77bc0 "  ZL", num_io_bytes=65536) at lz.c:524
#6  0x00007fcb6459cdc0 in red_lz_compress_image (dcc=0x7fcaf9daf290, 
    dest=0x7fcb0e9fa8a0, src=0x7fcb0e9fa8e0, o_comp_data=0x7fcb0e9fa910, 
    group_id=<value optimized out>) at red_worker.c:6038
#7  0x00007fcb645aa736 in red_marshall_image (rcc=0x7fcaf9daf290, 
    pipe_item=0x7fcb09c17960) at red_worker.c:8600
#8  display_channel_send_item (rcc=0x7fcaf9daf290, pipe_item=0x7fcb09c17960)
    at red_worker.c:8911
#9  0x00007fcb6458a583 in red_channel_client_send_item (rcc=0x7fcaf9daf290)
    at red_channel.c:507
#10 red_channel_client_push (rcc=0x7fcaf9daf290) at red_channel.c:1088
#11 0x00007fcb6458a9cb in red_channel_client_handle_message (
    rcc=0x7fcaf9daf290, size=1, type=<value optimized out>, 
    message=0x7fcaf9ea47e0) at red_channel.c:1175
#12 0x00007fcb6458a20b in red_peer_handle_incoming (rcc=0x7fcaf9daf290)
    at red_channel.c:272
#13 red_channel_client_receive (rcc=0x7fcaf9daf290) at red_channel.c:294
#14 0x00007fcb6458aa9c in red_channel_client_event (fd=<value optimized out>, 
    event=<value optimized out>, data=0x7fcaf9daf290) at red_channel.c:1204
#15 0x00007fcb645af88e in red_worker_main (arg=<value optimized out>)
    at red_worker.c:11782
#16 0x00007fcb65d6d851 in start_thread (arg=0x7fcb0e9fb700)
    at pthread_create.c:301
#17 0x00007fcb63e2c90d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 1 (Thread 0x7fcb66382980 (LWP 15058)):
#0  0x00007fcb63e254f3 in select () at ../sysdeps/unix/syscall-template.S:82
#1  0x00007fcb66412880 in main_loop_wait (timeout=1000)
    at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:3968
#2  0x00007fcb664348ca in kvm_main_loop ()
    at /usr/src/debug/qemu-kvm-0.12.1.2/qemu-kvm.c:2244
#3  0x00007fcb66415678 in main_loop (argc=56, argv=<value optimized out>, 
    envp=<value optimized out>) at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:4187
#4  main (argc=56, argv=<value optimized out>, envp=<value optimized out>)
    at /usr/src/debug/qemu-kvm-0.12.1.2/vl.c:6524

Version-Release number of selected component (if applicable):
RHEL6.4 Alpha host/client/guest
# rpm -qa | egrep "qemu-kvm|spice-server|spice-gtk|virt-viewer"
qemu-kvm-0.12.1.2-2.334.el6.x86_64
qemu-kvm-debuginfo-0.12.1.2-2.334.el6.x86_64
virt-viewer-0.5.2-16.el6.x86_64
spice-gtk-0.14-4.el6.x86_64
spice-gtk-python-0.14-4.el6.x86_64
spice-server-debuginfo-0.12.0-1.el6.x86_64
spice-server-0.12.0-1.el6.x86_64

How reproducible:
Very often (matter of time)

Steps to Reproduce:
1. Connect to RHEL6.4 machine with remote-viewer
2. Perform usual user actions
  
Actual results:
Abort hit

Expected results:
No abort

Additional info: