BXVGA: Disallow resolutions higher than 4096x2160

There's no sense in allowing arbitrarily huge resolutions. Instead, we
now cap the screen size at 4K DCI resolution and will reject attempts
to go bigger with EINVAL.

1 files changed, 5 insertions, 0 deletions

diff --git a/Kernel/Devices/BXVGADevice.cpp b/Kernel/Devices/BXVGADevice.cpp
index 47730d9936..474b8a897f 100644
--- a/Kernel/Devices/BXVGADevice.cpp
+++ b/Kernel/Devices/BXVGADevice.cpp
@@ -33,6 +33,9 @@
 #include <LibC/errno_numbers.h>
 #include <LibC/sys/ioctl_numbers.h>
 
+#define MAX_RESOLUTION_WIDTH 4096
+#define MAX_RESOLUTION_HEIGHT 2160
+
 #define VBE_DISPI_IOPORT_INDEX 0x01CE
 #define VBE_DISPI_IOPORT_DATA 0x01CF
 
@@ -167,6 +170,8 @@ int BXVGADevice::ioctl(FileDescription&, unsigned request, unsigned arg)
         auto* resolution = (FBResolution*)arg;
         if (!current->process().validate_read_typed(resolution) || !current->process().validate_write_typed(resolution))
             return -EFAULT;
+        if (resolution->width > MAX_RESOLUTION_WIDTH || resolution->height > MAX_RESOLUTION_HEIGHT)
+            return -EINVAL;
         set_resolution(resolution->width, resolution->height);
         resolution->pitch = m_framebuffer_pitch;
         resolution->width = m_framebuffer_width;