Am 08.02.2012 14:08, schrieb Kenneth Graunke:
> Some applications, such as Regnum Online, appear to pass invalid
> start/end values to glDrawRangeElements. In particular, the 'start'
> index sometimes exceeds the maximum array element. This is clearly
> invalid behavior, and although the spec isn't clear, seems to result
> in undefined, implementation-specific behavior.
>
> This patch takes the conservative approach and simply ignores the range,
> while issuing a warning indicating that the application is broken and
> should be fixed.
>
> NOTE: This is a candidate for release branches.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45214
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=44701
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=41152
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=40361
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=28138
> Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
> ---
> src/mesa/vbo/vbo_exec_array.c | 25 +++++++++++++++++++++++++
> 1 files changed, 25 insertions(+), 0 deletions(-)
>
> diff --git a/src/mesa/vbo/vbo_exec_array.c b/src/mesa/vbo/vbo_exec_array.c
> index ec4cb4f..c26a8cd 100644
> --- a/src/mesa/vbo/vbo_exec_array.c
> +++ b/src/mesa/vbo/vbo_exec_array.c
> @@ -858,6 +858,7 @@ vbo_exec_DrawRangeElementsBaseVertex(GLenum mode,
> const GLvoid *indices,
> GLint basevertex)
> {
> + static GLuint warnCount = 0;
> GET_CURRENT_CONTEXT(ctx);
>
> if (MESA_VERBOSE & VERBOSE_DRAW)
> @@ -870,6 +871,30 @@ vbo_exec_DrawRangeElementsBaseVertex(GLenum mode,
> type, indices, basevertex ))
> return;
>
> + if ((int)(start + basevertex) < 0 ||
> + start + basevertex >= ctx->Array.ArrayObj->_MaxElement) {
I don't quite agree with this; if you only want to warn if the range is
not plausible then it must be end + basevertex < 0 or start + basevertex
>= _MaxElement, i.e. all possible indices are outside of the array.
start + basevertex < 0 would be just fine by the reasoning that end +
basevertex >= _MaxElement is also ok.
> + /* The application requested we draw using a range of indices that's
> + * outside the bounds of the current VBO. This is invalid and appears
> + * to give undefined results. The safest thing to do is to simply
> + * ignore the range, in case the application botched their range
> tracking
> + * but did provide valid indices. Also issue a warning indicating that
> + * the application is broken.
> + */
> + if (warnCount++ < 10) {
> + _mesa_warning(ctx, "glDrawRangeElements(start %u, end %u, "
> + "basevertex %d, count %d, type 0x%x, indices=%p):\n"
> + "\tstart is out of bounds (max=%u); ignoring range.\n"
> + "\tThis should be fixed in the application.",
> + start, end, basevertex, count, type, indices,
> + ctx->Array.ArrayObj->_MaxElement - 1);
> + }
The warning text would also need some adjustment to account for end
being possibly wrong.
> +
> + /* Just do an ordinary glDrawElementsBaseVertex(). */
> + vbo_validated_drawrangeelements(ctx, mode, GL_FALSE, ~0, ~0,
> + count, type, indices, basevertex, 1);
> + return;
> + }
> +
> /* NOTE: It's important that 'end' is a reasonable value.
> * in _tnl_draw_prims(), we use end to determine how many vertices
> * to transform. If it's too large, we can unnecessarily split prims
Roland
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