Bug#405803: [Mesa3d-dev] Blender extrusion makes X SIGSEGV

[Julien Cristau]

tag 405803 pending
thanks

Hi,

I'll upload mesa with the backported patch in a moment, with the
attached NMU diff.
Note that to get the bug completely fixed, the X server will probably
have to be rebuilt against the new mesa source.

Cheers,
Julien
-------------- next part --------------
diff -u mesa-6.5.1/debian/changelog mesa-6.5.1/debian/changelog
--- mesa-6.5.1/debian/changelog
+++ mesa-6.5.1/debian/changelog
@@ -1,3 +1,13 @@
+mesa (6.5.1-0.6) unstable; urgency=medium
+
+  * Non-maintainer upload.
+  * Backport a fix from mesa 6.5.2 to mesa 6.5.1 which:
+     - fixes braces around the ASSERT macro;
+     - fixes a clipping problem, which leads to systematic segfaults of the
+       X server (Closes: #405803).
+
+ -- Cyril Brulebois <cyril.brulebois at enst-bretagne.fr>  Thu, 22 Feb 2007 21:08:56 +0100
+
 mesa (6.5.1-0.5) unstable; urgency=low
 
   * Non-maintainer upload.
only in patch2:
unchanged:
--- mesa-6.5.1.orig/src/mesa/tnl/t_vb_cliptmp.h
+++ mesa-6.5.1/src/mesa/tnl/t_vb_cliptmp.h
@@ -125,6 +125,7 @@
    GLfloat t0 = 0;
    GLfloat t1 = 0;
    GLuint p;
+   const GLuint v0_orig = v0;
 
    if (mask & 0x3f) {
       LINE_CLIP( CLIP_RIGHT_BIT,  -1,  0,  0, 1 );
@@ -153,12 +154,18 @@
       v0 = newvert;
       newvert++;
    }
-   else
+   else {
       ASSERT(t0 == 0.0);
+   }
 
    if (VB->ClipMask[v1]) {
-      INTERP_4F( t1, coord[newvert], coord[v1], coord[v0] );
-      interp( ctx, t1, newvert, v1, v0, GL_FALSE );
+     /* Note: we need to use vertex v0_orig when computing the new
+      * interpolated/clipped vertex position, not the current v0 which
+      * may have got set when we clipped the other end of the line!
+      */
+
+      INTERP_4F( t1, coord[newvert], coord[v1], coord[v0_orig] );
+      interp( ctx, t1, newvert, v1, v0_orig, GL_FALSE );
 
       if (ctx->Light.ShadeModel == GL_FLAT)
 	 tnl->Driver.Render.CopyPV( ctx, newvert, v1 );
@@ -167,8 +174,9 @@
 
       newvert++;
    }
-   else
+   else {
       ASSERT(t1 == 0.0);
+   }
 
    tnl->Driver.Render.ClippedLine( ctx, v0, v1 );
 }