[PULL 0/2] Vga 20200302 patches

[PULL 0/2] Vga 20200302 patches

[Gerd Hoffmann]

The following changes since commit e0175b71638cf4398903c0d25f93fe62e0606389:

  Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20200228' into staging (2020-02-28 16:39:27 +0000)

are available in the Git repository at:

  git://git.kraxel.org/qemu tags/vga-20200302-pull-request

for you to fetch changes up to 44b5c1ebfa5db337714180e9d4a8d525da5595d6:

  qxl: map rom r/o (2020-03-02 08:24:36 +0100)

----------------------------------------------------------------
vga: bugfixes for qxl and edid generator.

----------------------------------------------------------------

Anton V. Boyarshinov (1):
  Arithmetic error in EDID generation fixed

Gerd Hoffmann (1):
  qxl: map rom r/o

 hw/display/edid-generate.c | 4 ++--
 hw/display/qxl.c           | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

-- 
2.18.2

[PULL 1/2] Arithmetic error in EDID generation fixed

[Gerd Hoffmann]

From: "Anton V. Boyarshinov" <boyarsh@altlinux.org>

To calculate screen size in centimeters we should calculate:
pixels/dpi*2.54
but not
pixels*dpi/2540

Using wrong formula we actually get 65 DPI and very small fonts.

Signed-off-by: Anton V. Boyarshinov <boyarsh@altlinux.org>
Message-id: 20200226122054.366b9cda@table.localdomain
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/display/edid-generate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/display/edid-generate.c b/hw/display/edid-generate.c
index 75c945a94813..e58472fde501 100644
--- a/hw/display/edid-generate.c
+++ b/hw/display/edid-generate.c
@@ -360,8 +360,8 @@ void qemu_edid_generate(uint8_t *edid, size_t size,
     edid[20] = 0xa5;
 
     /* screen size: undefined */
-    edid[21] = info->prefx * info->dpi / 2540;
-    edid[22] = info->prefy * info->dpi / 2540;
+    edid[21] = info->prefx * 254 / 100 / info->dpi;
+    edid[22] = info->prefy * 254 / 100 / info->dpi;
 
     /* display gamma: 2.2 */
     edid[23] = 220 - 100;
-- 
2.18.2

[PULL 2/2] qxl: map rom r/o

[Gerd Hoffmann]

Map qxl rom read-only into the guest, so the guest can't tamper with the
content.  qxl has a shadow copy of the rom to deal with that, but the
shadow doesn't cover the mode list.  A privilidged user in the guest can
manipulate the mode list and that to trick qemu into oob reads, leading
to a DoS via segfault if that read access happens to hit unmapped memory.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200225055920.17261-2-kraxel@redhat.com
---
 hw/display/qxl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/display/qxl.c b/hw/display/qxl.c
index 21a43a1d5ec2..227da69a50d9 100644
--- a/hw/display/qxl.c
+++ b/hw/display/qxl.c
@@ -2136,7 +2136,7 @@ static void qxl_realize_common(PCIQXLDevice *qxl, Error **errp)
     pci_set_byte(&config[PCI_INTERRUPT_PIN], 1);
 
     qxl->rom_size = qxl_rom_size();
-    memory_region_init_ram(&qxl->rom_bar, OBJECT(qxl), "qxl.vrom",
+    memory_region_init_rom(&qxl->rom_bar, OBJECT(qxl), "qxl.vrom",
                            qxl->rom_size, &error_fatal);
     init_qxl_rom(qxl);
     init_qxl_ram(qxl);
-- 
2.18.2

Re: [PULL 0/2] Vga 20200302 patches

[Peter Maydell]

On Mon, 2 Mar 2020 at 09:19, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> The following changes since commit e0175b71638cf4398903c0d25f93fe62e0606389:
>
>   Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20200228' into staging (2020-02-28 16:39:27 +0000)
>
> are available in the Git repository at:
>
>   git://git.kraxel.org/qemu tags/vga-20200302-pull-request
>
> for you to fetch changes up to 44b5c1ebfa5db337714180e9d4a8d525da5595d6:
>
>   qxl: map rom r/o (2020-03-02 08:24:36 +0100)
>
> ----------------------------------------------------------------
> vga: bugfixes for qxl and edid generator.
>
> ----------------------------------------------------------------


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/5.0
for any user-visible changes.

-- PMM

Re: [PULL 1/2] Arithmetic error in EDID generation fixed

[Stefan Weil]

Am 02.03.20 um 10:18 schrieb Gerd Hoffmann:

> From: "Anton V. Boyarshinov" <boyarsh@altlinux.org>
>
> To calculate screen size in centimeters we should calculate:
> pixels/dpi*2.54
> but not
> pixels*dpi/2540
>
> Using wrong formula we actually get 65 DPI and very small fonts.
>
> Signed-off-by: Anton V. Boyarshinov <boyarsh@altlinux.org>
> Message-id: 20200226122054.366b9cda@table.localdomain
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/display/edid-generate.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/display/edid-generate.c b/hw/display/edid-generate.c
> index 75c945a94813..e58472fde501 100644
> --- a/hw/display/edid-generate.c
> +++ b/hw/display/edid-generate.c
> @@ -360,8 +360,8 @@ void qemu_edid_generate(uint8_t *edid, size_t size,
>      edid[20] = 0xa5;
>  
>      /* screen size: undefined */
> -    edid[21] = info->prefx * info->dpi / 2540;
> -    edid[22] = info->prefy * info->dpi / 2540;
> +    edid[21] = info->prefx * 254 / 100 / info->dpi;
> +    edid[22] = info->prefy * 254 / 100 / info->dpi;


Gerd, the required rounding (see my previous e-mail) for both values is
still missing.

Cheers,

Stefan