The reason for this bug is memory corruption in glibc's memory chunk
header that is in front of some bitmap pixman is allocating and
maintaining as image->bits.free_me. I set a memory watchpoint to this
memory location and this code here triggered it and corrupted what seems
to be a memory chunk size indicator, which upon free() causes print of
'invalid pointer' by glibc:
Thread 1 "qemu-system-x86" hit Hardware watchpoint 2: *0x7f6160361d88
Old value = 3145749
New value = 0
vga_draw_line8 (vga=vga@entry=0x556d68549b30, d=0x7f6160361d80 "",
d@entry=0x7f61603615e0 "", addr=983528, width=<optimized out>)
at /home/stefanb/tmp/qemu-tip/hw/display/vga-helpers.h:297
297 ((uint32_t *)d)[3] = palette[vga_read_byte(vga, addr + 3)];
(gdb) bt
#0 vga_draw_line8 (vga=vga@entry=0x556d68549b30, d=0x7f6160361d80 "",
d@entry=0x7f61603615e0 "", addr=983528, width=<optimized out>)
at /home/stefanb/tmp/qemu-tip/hw/display/vga-helpers.h:297
#1 0x0000556d659918ee in vga_draw_graphic (full_update=0, s=0x556d68549b30) at
/home/stefanb/tmp/qemu-tip/hw/display/vga.c:1695
#2 vga_update_display (opaque=0x556d68549b30) at
/home/stefanb/tmp/qemu-tip/hw/display/vga.c:1782
#3 0x0000556d65c0cd92 in vnc_refresh (dcl=0x556d683055a8) at ui/vnc.c:3046
#4 0x0000556d65bff702 in dpy_refresh (s=0x556d686be540) at ui/console.c:1658
#5 gui_update (opaque=0x556d686be540) at ui/console.c:205
#6 0x0000556d65d0deac in timerlist_run_timers (timer_list=0x556d66de0e00) at
util/qemu-timer.c:536
#7 0x0000556d65d0e0f7 in qemu_clock_run_timers (type=QEMU_CLOCK_REALTIME) at
util/qemu-timer.c:547
#8 qemu_clock_run_all_timers () at util/qemu-timer.c:674
#9 0x0000556d65d0e5d1 in main_loop_wait (nonblocking=<optimized out>) at
util/main-loop.c:503
#10 0x0000556d65a5f2ee in main_loop () at vl.c:1865
#11 0x0000556d658ff166 in main (argc=<optimized out>, argv=<optimized out>,
envp=<optimized out>) at vl.c:4643
--
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https://bugs.launchpad.net/bugs/1784900
Title:
QEMU (frontend) crashes upon warm reboot with virtio-gpu device and
vga=775 on Linux cmdline
Status in QEMU:
New
Bug description:
With vga=775 on the Linux command line a first boot of the VM running
Linux works fine. After a warm reboot it crashes during Linux boot.
The VM was used remotely via virt-manager and VNC.
Bisecting the code lead to the following patch that introduced the
bug:
commit 1fccd7c5a9a722a9cbf1bc91693f4618034f01ac (HEAD, refs/bisect/bad)
Author: Gerd Hoffmann <kra...@redhat.com>
Date: Mon Jul 2 18:24:43 2018 +0200
virtio-gpu: disable scanout when backing resource is destroyed
Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Message-id: 20180702162443.16796-4-kra...@redhat.com
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 336dc59007..08cd567218 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -430,6 +430,16 @@ static void virtio_gpu_disable_scanout(VirtIOGPU *g, int
scanout_id)
static void virtio_gpu_resource_destroy(VirtIOGPU *g,
struct virtio_gpu_simple_resource
*res)
{
+ int i;
+
+ if (res->scanout_bitmask) {
+ for (i = 0; i < g->conf.max_outputs; i++) {
+ if (res->scanout_bitmask & (1 << i)) {
+ virtio_gpu_disable_scanout(g, i);
+ }
+ }
+ }
+
pixman_image_unref(res->image);
virtio_gpu_cleanup_mapping(res);
QTAILQ_REMOVE(&g->reslist, res, next);
Reported backtraces can be found here:
https://paste.fedoraproject.org/paste/OUDEfCk1IY7xiy0I0PDlkw
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