xf86-video-intel: src/i830_display.c

[Jesse Barnes]

 src/i830_display.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

New commits:
commit 7332132a79e5b5c208d43e93dfe0c8b12eb1728d
Author: Jesse Barnes <jbarnes at jbarnes-t61.(none)>
Date:   Mon Jul 7 10:48:56 2008 -0700

    Improve FBC size checking
    
    In hindsight, this is obvious, since nowhere do we tell the FBC unit how much
    memory it has available.  We need to make sure the compressed buffer is big
    enough to handle the uncompresed buffer, both in terms of vertical size and
    total framebuffer size, or the compressor could overwrite the memory
    immediately following the compressed buffer.

diff --git a/src/i830_display.c b/src/i830_display.c
index df3a6be..306fed4 100644
--- a/src/i830_display.c
+++ b/src/i830_display.c
@@ -693,6 +693,7 @@ i830_use_fb_compression(xf86CrtcPtr crtc)
     xf86CrtcConfigPtr xf86_config = XF86_CRTC_CONFIG_PTR(pScrn);
     I830Ptr pI830 = I830PTR(pScrn);
     I830CrtcPrivatePtr	intel_crtc = crtc->driver_private;
+    unsigned long uncompressed_size;
     int plane = (intel_crtc->plane == 0 ? FBC_CTL_PLANEA : FBC_CTL_PLANEB);
     int i, count = 0;
 
@@ -724,6 +725,19 @@ i830_use_fb_compression(xf86CrtcPtr crtc)
 	  pScrn->bitsPerPixel == 32)) /* mode_set dtrt if fbc is in use */
 	return FALSE;
 
+    /* Can't cache more lines than we can track */
+    if (crtc->mode.VDisplay > FBC_LL_SIZE)
+	return FALSE;
+
+    /*
+     * Make sure the compressor doesn't go past the end of our compressed
+     * buffer if the uncompressed size is large.
+     */
+    uncompressed_size = crtc->mode.HDisplay * crtc->mode.VDisplay *
+	pI830->cpp;
+    if (pI830->compressed_front_buffer->size < uncompressed_size)
+	return FALSE;
+
     /*
      * No checks for pixel multiply, incl. horizontal, or interlaced modes
      * since they're currently unused.