ValidateDrawElements: check count > 0 then compute the index range

Otherwise glDrawElements(GL_TRIANGLES, -1, nullptr) would crash. This was found by an ASSERT in ComputeIndexRange triggered by dEQP-GLES2.functional.negative_api.vertex_array.draw_elements BUG= Change-Id: I5269031fa35aa6403c844561e04158361ee7950f Reviewed-on: https://chromium-review.googlesource.com/292710Tested-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

ValidateDrawElements: check count > 0 then compute the index range
18a2fb3a · Corentin Wallez · b195643c · 18a2fb3a
Commit 18a2fb3a authored Aug 10, 2015 by Corentin Wallez
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Showing with 13 additions and 9 deletions

validationES.cpp src/libANGLE/validationES.cpp +13 -9

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--- a/src/libANGLE/validationES.cpp
+++ b/src/libANGLE/validationES.cpp
@@ -1406,7 +1406,7 @@ bool ValidateCopyTexImageParametersBase(gl::Context *context, GLenum target, GLi
    return true;
 }

-static bool ValidateDrawBase(Context *context, GLenum mode, GLsizei count, GLsizei maxVertex, GLsizei primcount)
+static bool ValidateDrawBase(Context *context, GLenum mode, GLsizei count, GLsizei primcount)
 {
    switch (mode)
    {
@@ -1471,12 +1471,6 @@ static bool ValidateDrawBase(Context *context, GLenum mode, GLsizei count, GLsiz
        return false;
    }

-    // Buffer validations
-    if (!ValidateDrawAttribs(context, primcount, maxVertex))
-    {
-        return false;
-    }
-
    // Uniform buffer validation
    for (unsigned int uniformBlockIndex = 0; uniformBlockIndex < program->getActiveUniformBlockCount(); uniformBlockIndex++)
    {
@@ -1531,7 +1525,12 @@ bool ValidateDrawArrays(Context *context, GLenum mode, GLint first, GLsizei coun
        return false;
    }

-    if (!ValidateDrawBase(context, mode, count, count, primcount))
+    if (!ValidateDrawBase(context, mode, count, primcount))
+    {
+        return false;
+    }
+
+    if (!ValidateDrawAttribs(context, primcount, count))
    {
        return false;
    }
@@ -1664,6 +1663,11 @@ bool ValidateDrawElements(Context *context, GLenum mode, GLsizei count, GLenum t
        return false;
    }

+    if (!ValidateDrawBase(context, mode, count, primcount))
+    {
+        return false;
+    }
+
    // Use max index to validate if our vertex buffers are large enough for the pull.
    // TODO: offer fast path, with disabled index validation.
    // TODO: also disable index checking on back-ends that are robust to out-of-range accesses.
@@ -1682,7 +1686,7 @@ bool ValidateDrawElements(Context *context, GLenum mode, GLsizei count, GLenum t
        *indexRangeOut = ComputeIndexRange(type, indices, count);
    }

-    if (!ValidateDrawBase(context, mode, count, static_cast<GLsizei>(indexRangeOut->end), primcount))
+    if (!ValidateDrawAttribs(context, primcount, static_cast<GLsizei>(indexRangeOut->end)))
    {
        return false;
    }