Mesa (10.2): glsl: fix use-after free bug/crash in ast_declarator_list:: hir()

[Ian Romanick]

Module: Mesa
Branch: 10.2
Commit: 55b9effa4a23755232e433d3da4f422a1f74fd82
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=55b9effa4a23755232e433d3da4f422a1f74fd82

Author: Brian Paul <brianp at vmware.com>
Date:   Fri May 23 14:59:33 2014 -0600

glsl: fix use-after free bug/crash in ast_declarator_list::hir()

The call to get_variable_being_redeclared() may delete 'var' so we
can't reference var->name afterward.  We fix that by examining the
var's name before making that call.

Fixes valgrind warnings and possible crash when running the piglit
tests/spec/glsl-1.30/execution/clipping/vs-clip-distance-in-param.shader_test
test (and probably others).

Cc: "10.1 10.2" <mesa-stable at lists.freedesktop.org>

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
(cherry picked from commit f9cecca7a6e3d9ff231075381b88d179e153a5a4)

---

 src/glsl/ast_to_hir.cpp |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 7516c33..332f934 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -3652,11 +3652,15 @@ ast_declarator_list::hir(exec_list *instructions,
        * instruction stream.
        */
       exec_list initializer_instructions;
+
+      /* Examine var name here since var may get deleted in the next call */
+      bool var_is_gl_id = (strncmp(var->name, "gl_", 3) == 0);
+
       ir_variable *earlier =
          get_variable_being_redeclared(var, decl->get_location(), state,
                                        false /* allow_all_redeclarations */);
       if (earlier != NULL) {
-         if (strncmp(var->name, "gl_", 3) == 0 &&
+         if (var_is_gl_id &&
              earlier->data.how_declared == ir_var_declared_in_block) {
             _mesa_glsl_error(&loc, state,
                              "`%s' has already been redeclared using "