[Mesa-dev] [PATCH 1/2] glsl: fix heap-use-after-free in ast_declarator_list::hir()

[Samuel Iglesias Gonsálvez]

The get_variable_being_redeclared() function can free 'var' because
a re-declaration of an unsized array variable can establish the size, so
we set the array type to the 'earlier' declaration and free 'var' as it is
not needed anymore.

However, the same 'var' is referenced later in ast_declarator_list::hir().

This patch fixes it by picking the ir_variable_mode from the proper
ir_variable.

This error was detected by Address Sanitizer.

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Suggested-by: Ian Romanick <ian.d.romanick at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99677
Cc: "17.0" <mesa-stable at lists.freedesktop.org>
---
 src/compiler/glsl/ast_to_hir.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index b31b61d1ed6..3613161472d 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -5262,11 +5262,13 @@ ast_declarator_list::hir(exec_list *instructions,
           *     sized by an earlier input primitive layout qualifier, when
           *     present, as per the following table."
           */
+         const enum ir_variable_mode mode = (const enum ir_variable_mode)
+            (earlier == NULL ? var->data.mode : earlier->data.mode);
          const bool implicitly_sized =
-            (var->data.mode == ir_var_shader_in &&
+            (mode == ir_var_shader_in &&
              state->stage >= MESA_SHADER_TESS_CTRL &&
              state->stage <= MESA_SHADER_GEOMETRY) ||
-            (var->data.mode == ir_var_shader_out &&
+            (mode == ir_var_shader_out &&
              state->stage == MESA_SHADER_TESS_CTRL);
 
          if (t->is_unsized_array() && !implicitly_sized)
-- 
2.11.0