[Mesa-dev] [Mesa-stable] [PATCH 2/4] glsl: fix use-after-free when processing array re-declarations
Ian Romanick
idr at freedesktop.org
Wed Feb 22 20:44:55 UTC 2017
I thought we already landed a different patch for this. I'll look through
the archives when I get back in front of a computer...
On February 22, 2017 11:05:26 AM Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> When determining whether the array is implicitly sized, we must avoid
> accessing var->data.mode (around line 5270), because var may have been
> deleted.
>
> Instead of adding yet another ternary condition based on earlier == NULL,
> refactor get_variable_being_redeclared so that we do not keep dangling
> pointers around.
>
> Found by ASAN in GL45-CTS.gtf21.GL.build.array10_frag.
>
> Cc: mesa-stable at lists.freedesktop.org
> ---
> src/compiler/glsl/ast_to_hir.cpp | 55 ++++++++++++++++++++++------------------
> 1 file changed, 30 insertions(+), 25 deletions(-)
>
> diff --git a/src/compiler/glsl/ast_to_hir.cpp
> b/src/compiler/glsl/ast_to_hir.cpp
> index b90ad97..57a9db9 100644
> --- a/src/compiler/glsl/ast_to_hir.cpp
> +++ b/src/compiler/glsl/ast_to_hir.cpp
> @@ -3942,44 +3942,50 @@ apply_type_qualifier_to_variable(const struct
> ast_type_qualifier *qual,
> "the shared storage qualifiers can only be used with "
> "compute shaders");
> }
>
> apply_image_qualifier_to_variable(qual, var, state, loc);
> }
>
> /**
> * Get the variable that is being redeclared by this declaration
> *
> + * \p pvar is changed to point to an existing variable in the current scope if
> + * the declaration that it initially points to is a redeclaration.
> + *
> + * The declaration originally pointed to by \p pvar may be deleted.
> + *
> * Semantic checks to verify the validity of the redeclaration are also
> * performed. If semantic checks fail, compilation error will be emitted via
> - * \c _mesa_glsl_error, but a non-\c NULL pointer will still be returned.
> + * \c _mesa_glsl_error, but a non-\c NULL pointer will still be provided.
> *
> * \returns
> - * A pointer to an existing variable in the current scope if the declaration
> - * is a redeclaration, \c NULL otherwise.
> + * Whether the declaration is a redeclaration.
> */
> -static ir_variable *
> -get_variable_being_redeclared(ir_variable *var, YYLTYPE loc,
> +static bool
> +get_variable_being_redeclared(ir_variable **pvar, YYLTYPE loc,
> struct _mesa_glsl_parse_state *state,
> bool allow_all_redeclarations)
> {
> + ir_variable *var = *pvar;
> +
> /* Check if this declaration is actually a re-declaration, either to
> * resize an array or add qualifiers to an existing variable.
> *
> * This is allowed for variables in the current scope, or when at
> * global scope (for built-ins in the implicit outer scope).
> */
> ir_variable *earlier = state->symbols->get_variable(var->name);
> if (earlier == NULL ||
> (state->current_function != NULL &&
> !state->symbols->name_declared_this_scope(var->name))) {
> - return NULL;
> + return false;
> }
>
>
> /* From page 24 (page 30 of the PDF) of the GLSL 1.50 spec,
> *
> * "It is legal to declare an array without a size and then
> * later re-declare the same name as an array of the same
> * type and specify a size."
> */
> if (earlier->type->is_unsized_array() && var->type->is_array()
> @@ -4082,21 +4088,22 @@ get_variable_being_redeclared(ir_variable *var,
> YYLTYPE loc,
> var->name);
> } else if (earlier->type != var->type) {
> _mesa_glsl_error(&loc, state,
> "redeclaration of `%s' has incorrect type",
> var->name);
> }
> } else {
> _mesa_glsl_error(&loc, state, "`%s' redeclared", var->name);
> }
>
> - return earlier;
> + *pvar = earlier;
> + return true;
> }
>
> /**
> * Generate the IR for an initializer in a variable declaration
> */
> ir_rvalue *
> process_initializer(ir_variable *var, ast_declaration *decl,
> ast_fully_specified_type *type,
> exec_list *initializer_instructions,
> struct _mesa_glsl_parse_state *state)
> @@ -5196,56 +5203,54 @@ ast_declarator_list::hir(exec_list *instructions,
> * list. This list will be added to the instruction stream (below) after
> * the declaration is added. This is done because in some cases (such as
> * redeclarations) the declaration may not actually be added to the
> * instruction stream.
> */
> exec_list initializer_instructions;
>
> /* Examine var name here since var may get deleted in the next call */
> bool var_is_gl_id = is_gl_identifier(var->name);
>
> - ir_variable *earlier =
> - get_variable_being_redeclared(var, decl->get_location(), state,
> + bool is_redeclaration =
> + get_variable_being_redeclared(&var, decl->get_location(), state,
> false /* allow_all_redeclarations */);
> - if (earlier != NULL) {
> + if (is_redeclaration) {
> if (var_is_gl_id &&
> - earlier->data.how_declared == ir_var_declared_in_block) {
> + var->data.how_declared == ir_var_declared_in_block) {
> _mesa_glsl_error(&loc, state,
> "`%s' has already been redeclared using "
> - "gl_PerVertex", earlier->name);
> + "gl_PerVertex", var->name);
> }
> - earlier->data.how_declared = ir_var_declared_normally;
> + var->data.how_declared = ir_var_declared_normally;
> }
>
> if (decl->initializer != NULL) {
> - result = process_initializer((earlier == NULL) ? var : earlier,
> - decl, this->type,
> + result = process_initializer(var, decl, this->type,
> &initializer_instructions, state);
> } else {
> validate_array_dimensions(var_type, state, &loc);
> }
>
> /* From page 23 (page 29 of the PDF) of the GLSL 1.10 spec:
> *
> * "It is an error to write to a const variable outside of
> * its declaration, so they must be initialized when
> * declared."
> */
> if (this->type->qualifier.flags.q.constant && decl->initializer == NULL) {
> _mesa_glsl_error(& loc, state,
> "const declaration of `%s' must be initialized",
> decl->identifier);
> }
>
> if (state->es_shader) {
> - const glsl_type *const t = (earlier == NULL)
> - ? var->type : earlier->type;
> + const glsl_type *const t = var->type;
>
> /* Skip the unsized array check for TCS/TES/GS inputs & TCS outputs.
> *
> * The GL_OES_tessellation_shader spec says about inputs:
> *
> * "Declaring an array size is optional. If no size is specified,
> * it will be taken from the implementation-dependent maximum
> * patch size (gl_MaxPatchVertices)."
> *
> * and about TCS outputs:
> @@ -5286,21 +5291,21 @@ ast_declarator_list::hir(exec_list *instructions,
> */
> _mesa_glsl_error(& loc, state,
> "unsized array declarations are not allowed in "
> "GLSL ES");
> }
>
> /* If the declaration is not a redeclaration, there are a few additional
> * semantic checks that must be applied. In addition, variable that was
> * created for the declaration should be added to the IR stream.
> */
> - if (earlier == NULL) {
> + if (!is_redeclaration) {
> validate_identifier(decl->identifier, loc, state);
>
> /* Add the variable to the symbol table. Note that the initializer's
> * IR was already processed earlier (though it hasn't been emitted
> * yet), without the variable in scope.
> *
> * This differs from most C-like languages, but it follows the GLSL
> * specification. From page 28 (page 34 of the PDF) of the GLSL 1.50
> * spec:
> *
> @@ -7862,34 +7867,34 @@ ast_interface_block::hir(exec_list *instructions,
> var->data.matrix_layout = fields[i].matrix_layout;
> }
>
> if (var->data.mode == ir_var_shader_storage)
> apply_memory_qualifiers(var, fields[i]);
>
> /* Examine var name here since var may get deleted in the next call */
> bool var_is_gl_id = is_gl_identifier(var->name);
>
> if (redeclaring_per_vertex) {
> - ir_variable *earlier =
> - get_variable_being_redeclared(var, loc, state,
> + bool is_redeclaration =
> + get_variable_being_redeclared(&var, loc, state,
> true /* allow_all_redeclarations */);
> - if (!var_is_gl_id || earlier == NULL) {
> + if (!var_is_gl_id || !is_redeclaration) {
> _mesa_glsl_error(&loc, state,
> "redeclaration of gl_PerVertex can only "
> "include built-in variables");
> - } else if (earlier->data.how_declared ==
> ir_var_declared_normally) {
> + } else if (var->data.how_declared == ir_var_declared_normally) {
> _mesa_glsl_error(&loc, state,
> "`%s' has already been redeclared",
> - earlier->name);
> + var->name);
> } else {
> - earlier->data.how_declared = ir_var_declared_in_block;
> - earlier->reinit_interface_type(block_type);
> + var->data.how_declared = ir_var_declared_in_block;
> + var->reinit_interface_type(block_type);
> }
> continue;
> }
>
> if (state->symbols->get_variable(var->name) != NULL)
> _mesa_glsl_error(&loc, state, "`%s' redeclared", var->name);
>
> /* Propagate the "binding" keyword into this UBO/SSBO's fields.
> * The UBO declaration itself doesn't get an ir_variable unless it
> * has an instance name. This is ugly.
> --
> 2.9.3
>
> _______________________________________________
> mesa-stable mailing list
> mesa-stable at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-stable
More information about the mesa-dev
mailing list