Code simply asserts that there is no wraparound instead of handling it properly. The assert() can be triggered by the guest (must be privilidged inside the guest though). Fix it.
Buglink: https://bugs.launchpad.net/qemu/+bug/1880189 Cc: Li Qiang <liq...@163.com> Reported-by: Philippe Mathieu-Daudé <phi...@redhat.com> Signed-off-by: Gerd Hoffmann <kra...@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> Reviewed-by: Li Qiang <liq...@163.com> Message-id: 20200901140944.24101-1-kra...@redhat.com --- hw/display/cirrus_vga.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index 02d9ed0bd465..41e71af08a0f 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -640,10 +640,16 @@ static void cirrus_invalidate_region(CirrusVGAState * s, int off_begin, } for (y = 0; y < lines; y++) { - off_cur = off_begin; + off_cur = off_begin & s->cirrus_addr_mask; off_cur_end = ((off_cur + bytesperline - 1) & s->cirrus_addr_mask) + 1; - assert(off_cur_end >= off_cur); - memory_region_set_dirty(&s->vga.vram, off_cur, off_cur_end - off_cur); + if (off_cur_end >= off_cur) { + memory_region_set_dirty(&s->vga.vram, off_cur, off_cur_end - off_cur); + } else { + /* wraparound */ + memory_region_set_dirty(&s->vga.vram, off_cur, + s->cirrus_addr_mask + 1 - off_cur); + memory_region_set_dirty(&s->vga.vram, 0, off_cur_end); + } off_begin += off_pitch; } } -- 2.27.0
