| Message ID | 1390227620-23771-1-git-send-email-alevy@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 20 January 2014 14:20, Alon Levy <alevy@redhat.com> wrote: > Several small signedness / overflow corrections to qxl_create_guest_primary: > 1. use 64 bit unsigned for size to avoid overflow possible from two 32 > bit multiplicants. > 2. correct sign for requested_height > 3. add a more verbose error message when setting guest bug state (which > causes a complete guess blackout until reset, so it helps if it is > verbose). > > Signed-off-by: Alon Levy <alevy@redhat.com> > --- > hw/display/qxl.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/hw/display/qxl.c b/hw/display/qxl.c > index e4f172e..ba752b5 100644 > --- a/hw/display/qxl.c > +++ b/hw/display/qxl.c > @@ -1360,14 +1360,15 @@ static void qxl_create_guest_primary(PCIQXLDevice *qxl, int loadvm, > { > QXLDevSurfaceCreate surface; > QXLSurfaceCreate *sc = &qxl->guest_primary.surface; > - int size; > - int requested_height = le32_to_cpu(sc->height); > + uint64_t size; > + uint32_t requested_height = le32_to_cpu(sc->height); > int requested_stride = le32_to_cpu(sc->stride); > > size = abs(requested_stride) * requested_height; This is still doing a 32 x 32 multiply. You need to make at least one side of the multiply use a 64 bit type (via cast or by having it be a 64 bit type). You're also still potentially passing minimum-integer into abs. That should probably just be caught before we do the abs() since it will always mean the size is too large. thanks -- PMM
diff --git a/hw/display/qxl.c b/hw/display/qxl.c index e4f172e..ba752b5 100644 --- a/hw/display/qxl.c +++ b/hw/display/qxl.c @@ -1360,14 +1360,15 @@ static void qxl_create_guest_primary(PCIQXLDevice *qxl, int loadvm, { QXLDevSurfaceCreate surface; QXLSurfaceCreate *sc = &qxl->guest_primary.surface; - int size; - int requested_height = le32_to_cpu(sc->height); + uint64_t size; + uint32_t requested_height = le32_to_cpu(sc->height); int requested_stride = le32_to_cpu(sc->stride); size = abs(requested_stride) * requested_height; if (size > qxl->vgamem_size) { - qxl_set_guest_bug(qxl, "%s: requested primary larger then framebuffer" - " size", __func__); + qxl_set_guest_bug(qxl, "%s: requested primary larger than framebuffer" + " size %" PRIu64 " > %" PRIu32, __func__, size, + qxl->vgamem_size); return; }
Several small signedness / overflow corrections to qxl_create_guest_primary: 1. use 64 bit unsigned for size to avoid overflow possible from two 32 bit multiplicants. 2. correct sign for requested_height 3. add a more verbose error message when setting guest bug state (which causes a complete guess blackout until reset, so it helps if it is verbose). Signed-off-by: Alon Levy <alevy@redhat.com> --- hw/display/qxl.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)