Check pixmap allocation return value when creating glyphs

The driver may decide that the pixmap is too large or something and
fail to allocate a pixmap; not checking would lead to a segfault.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jamey Sharp <jamey@minilop.net>

render/render.c

@@ -1140,6 +1140,12 @@ ProcRenderAddGlyphs (ClientPtr client)
 						   width, height, depth,
 						   CREATE_PIXMAP_USAGE_GLYPH_PICTURE);
 
+		if (!pDstPix)
+		{
+		    err = BadAlloc;
+		    goto bail;
+		}
+
 		GlyphPicture (glyph)[screen] = pDst =
 			CreatePicture (0, &pDstPix->drawable,
 				       glyphSet->format,
@@ -1149,6 +1155,7 @@ ProcRenderAddGlyphs (ClientPtr client)
 		/* The picture takes a reference to the pixmap, so we
 		   drop ours. */
 		(pScreen->DestroyPixmap) (pDstPix);
+		pDstPix = NULL;
 
 		if (! pDst)
 		{