Re: [Mesa-dev] [PATCH v2] glsl: fix heap-use-after-free in ast_declarator_list::hir()
On Thu, 2017-02-09 at 13:34 +0100, Ian Romanick wrote: > NAK. > > The way the code is currently architected, if earlier is non-NULL, > var > should not be used. There are quite a few places where the callees > do > things like 'const glsl_type *const t = (earlier == NULL) ? var->type > : > earlier->type;'. This is a bit confusing, but this change muddles > that > and makes it worse. > > I think the actual use-after-free is in setting implicitly_sized at > line > 5265. I think doing something like > > const enum ir_variable_mode *mode = earlier == NULL > ? >data.mode : >data.mode; > const bool implicitly_sized = > (mode == ir_var_shader_in && > state->stage >= MESA_SHADER_TESS_CTRL && > state->stage <= MESA_SHADER_GEOMETRY) || > (mode == ir_var_shader_out && > state->stage == MESA_SHADER_TESS_CTRL); > > should also fix the problem. This should be tagged for stable. > Right. I'll do it. > After that fix, we may want to look at rearchitecting this code to be > less... confusing. The fundamental problem is > get_variable_being_redeclared is really trying to return two pieces > of > information, but it does this through a single variable. > > 1. Is this actually a redeclaration? > > 2. What is the variable that needs to be modified? > > When get_variable_being_redeclared returns NULL, it's not a > redeclaration, and the variable being modified is the ir_variable > passed > in. When it returns non-NULL, it is a redeclaration, and the > variable > being modified is the one returned. > > Maybe the function should always return non-NULL (returning either > 'earlier' or 'var') and have an extra parameter 'bool > *redeclaration'. > I think that would result in almost no changes to the second caller > and > several simplifications to the first caller. Thoughts? > Yeah, that could improve things. I am going to send two patches, one is the aforementioned fix (with Cc to mesa-stable@) and another with the refactor. Sam > On 02/07/2017 01:47 PM, Samuel Iglesias Gonsálvez wrote: > > 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 assign the pointer 'var' to the pointer > > 'earlier'. > > > > This error was detected by Address Sanitizer. > > > > v2: > > > > * Pointer-to-pointer assignment (Bartosz Tomczyk) > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99677 > > Signed-off-by: Samuel Iglesias Gonsálvez> > --- > > > > Another possibility is to use reference-to-pointer but it is a C++ > > thing. IIRC, we agreed on avoiding C++-specific features to make it > > easy for C developers, but I have no strong opinion for either > > option. > > > > src/compiler/glsl/ast_to_hir.cpp | 10 ++ > > 1 file changed, 6 insertions(+), 4 deletions(-) > > > > diff --git a/src/compiler/glsl/ast_to_hir.cpp > > b/src/compiler/glsl/ast_to_hir.cpp > > index b31b61d1ed6..93ba1d510fa 100644 > > --- a/src/compiler/glsl/ast_to_hir.cpp > > +++ b/src/compiler/glsl/ast_to_hir.cpp > > @@ -3958,10 +3958,12 @@ apply_type_qualifier_to_variable(const > > struct ast_type_qualifier *qual, > > * is a redeclaration, \c NULL otherwise. > > */ > > static ir_variable * > > -get_variable_being_redeclared(ir_variable *var, YYLTYPE loc, > > +get_variable_being_redeclared(ir_variable **var_pointer, YYLTYPE > > loc, > > struct _mesa_glsl_parse_state > > *state, > > bool allow_all_redeclarations) > > { > > + ir_variable *var = *var_pointer; > > + > > /* Check if this declaration is actually a re-declaration, > > either to > > * resize an array or add qualifiers to an existing variable. > > * > > @@ -3999,7 +4001,7 @@ get_variable_being_redeclared(ir_variable > > *var, YYLTYPE loc, > > > > earlier->type = var->type; > > delete var; > > - var = NULL; > > + *var_pointer = earlier; > > } else if ((state->ARB_fragment_coord_conventions_enable || > > state->is_version(150, 0)) > > && strcmp(var->name, "gl_FragCoord") == 0 > > @@ -5207,7 +5209,7 @@ ast_declarator_list::hir(exec_list > > *instructions, > > bool var_is_gl_id = is_gl_identifier(var->name); > > > > ir_variable *earlier = > > - get_variable_being_redeclared(var, decl->get_location(), > > state, > > + get_variable_being_redeclared(, decl->get_location(), > > state, > > false /* > > allow_all_redeclarations */); > > if (earlier != NULL) { > > if (var_is_gl_id && > > @@ -7873,7 +7875,7 @@
Re: [Mesa-dev] [PATCH v2] glsl: fix heap-use-after-free in ast_declarator_list::hir()
NAK. The way the code is currently architected, if earlier is non-NULL, var should not be used. There are quite a few places where the callees do things like 'const glsl_type *const t = (earlier == NULL) ? var->type : earlier->type;'. This is a bit confusing, but this change muddles that and makes it worse. I think the actual use-after-free is in setting implicitly_sized at line 5265. I think doing something like const enum ir_variable_mode *mode = earlier == NULL ? >data.mode : >data.mode; const bool implicitly_sized = (mode == ir_var_shader_in && state->stage >= MESA_SHADER_TESS_CTRL && state->stage <= MESA_SHADER_GEOMETRY) || (mode == ir_var_shader_out && state->stage == MESA_SHADER_TESS_CTRL); should also fix the problem. This should be tagged for stable. After that fix, we may want to look at rearchitecting this code to be less... confusing. The fundamental problem is get_variable_being_redeclared is really trying to return two pieces of information, but it does this through a single variable. 1. Is this actually a redeclaration? 2. What is the variable that needs to be modified? When get_variable_being_redeclared returns NULL, it's not a redeclaration, and the variable being modified is the ir_variable passed in. When it returns non-NULL, it is a redeclaration, and the variable being modified is the one returned. Maybe the function should always return non-NULL (returning either 'earlier' or 'var') and have an extra parameter 'bool *redeclaration'. I think that would result in almost no changes to the second caller and several simplifications to the first caller. Thoughts? On 02/07/2017 01:47 PM, Samuel Iglesias Gonsálvez wrote: > 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 assign the pointer 'var' to the pointer 'earlier'. > > This error was detected by Address Sanitizer. > > v2: > > * Pointer-to-pointer assignment (Bartosz Tomczyk) > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99677 > Signed-off-by: Samuel Iglesias Gonsálvez> --- > > Another possibility is to use reference-to-pointer but it is a C++ > thing. IIRC, we agreed on avoiding C++-specific features to make it > easy for C developers, but I have no strong opinion for either option. > > src/compiler/glsl/ast_to_hir.cpp | 10 ++ > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/src/compiler/glsl/ast_to_hir.cpp > b/src/compiler/glsl/ast_to_hir.cpp > index b31b61d1ed6..93ba1d510fa 100644 > --- a/src/compiler/glsl/ast_to_hir.cpp > +++ b/src/compiler/glsl/ast_to_hir.cpp > @@ -3958,10 +3958,12 @@ apply_type_qualifier_to_variable(const struct > ast_type_qualifier *qual, > * is a redeclaration, \c NULL otherwise. > */ > static ir_variable * > -get_variable_being_redeclared(ir_variable *var, YYLTYPE loc, > +get_variable_being_redeclared(ir_variable **var_pointer, YYLTYPE loc, >struct _mesa_glsl_parse_state *state, >bool allow_all_redeclarations) > { > + ir_variable *var = *var_pointer; > + > /* Check if this declaration is actually a re-declaration, either to > * resize an array or add qualifiers to an existing variable. > * > @@ -3999,7 +4001,7 @@ get_variable_being_redeclared(ir_variable *var, YYLTYPE > loc, > >earlier->type = var->type; >delete var; > - var = NULL; > + *var_pointer = earlier; > } else if ((state->ARB_fragment_coord_conventions_enable || >state->is_version(150, 0)) >&& strcmp(var->name, "gl_FragCoord") == 0 > @@ -5207,7 +5209,7 @@ ast_declarator_list::hir(exec_list *instructions, >bool var_is_gl_id = is_gl_identifier(var->name); > >ir_variable *earlier = > - get_variable_being_redeclared(var, decl->get_location(), state, > + get_variable_being_redeclared(, decl->get_location(), state, > false /* allow_all_redeclarations */); >if (earlier != NULL) { > if (var_is_gl_id && > @@ -7873,7 +7875,7 @@ ast_interface_block::hir(exec_list *instructions, > > if (redeclaring_per_vertex) { > ir_variable *earlier = > - get_variable_being_redeclared(var, loc, state, > + get_variable_being_redeclared(, loc, state, > true /* > allow_all_redeclarations */); > if (!var_is_gl_id || earlier == NULL) { > _mesa_glsl_error(, state, > ___ mesa-dev mailing list
Re: [Mesa-dev] [PATCH v2] glsl: fix heap-use-after-free in ast_declarator_list::hir()
Patch is: Tested-by: Bartosz TomczykI can confirm it fix use-after-free issue. On Tue, Feb 7, 2017 at 1:47 PM, Samuel Iglesias Gonsálvez < sigles...@igalia.com> wrote: > 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 assign the pointer 'var' to the pointer 'earlier'. > > This error was detected by Address Sanitizer. > > v2: > > * Pointer-to-pointer assignment (Bartosz Tomczyk) > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99677 > Signed-off-by: Samuel Iglesias Gonsálvez > --- > > Another possibility is to use reference-to-pointer but it is a C++ > thing. IIRC, we agreed on avoiding C++-specific features to make it > easy for C developers, but I have no strong opinion for either option. > > src/compiler/glsl/ast_to_hir.cpp | 10 ++ > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_ > hir.cpp > index b31b61d1ed6..93ba1d510fa 100644 > --- a/src/compiler/glsl/ast_to_hir.cpp > +++ b/src/compiler/glsl/ast_to_hir.cpp > @@ -3958,10 +3958,12 @@ apply_type_qualifier_to_variable(const struct > ast_type_qualifier *qual, > * is a redeclaration, \c NULL otherwise. > */ > static ir_variable * > -get_variable_being_redeclared(ir_variable *var, YYLTYPE loc, > +get_variable_being_redeclared(ir_variable **var_pointer, YYLTYPE loc, >struct _mesa_glsl_parse_state *state, >bool allow_all_redeclarations) > { > + ir_variable *var = *var_pointer; > + > /* Check if this declaration is actually a re-declaration, either to > * resize an array or add qualifiers to an existing variable. > * > @@ -3999,7 +4001,7 @@ get_variable_being_redeclared(ir_variable *var, > YYLTYPE loc, > >earlier->type = var->type; >delete var; > - var = NULL; > + *var_pointer = earlier; > } else if ((state->ARB_fragment_coord_conventions_enable || >state->is_version(150, 0)) >&& strcmp(var->name, "gl_FragCoord") == 0 > @@ -5207,7 +5209,7 @@ ast_declarator_list::hir(exec_list *instructions, >bool var_is_gl_id = is_gl_identifier(var->name); > >ir_variable *earlier = > - get_variable_being_redeclared(var, decl->get_location(), state, > + get_variable_being_redeclared(, decl->get_location(), state, > false /* allow_all_redeclarations > */); >if (earlier != NULL) { > if (var_is_gl_id && > @@ -7873,7 +7875,7 @@ ast_interface_block::hir(exec_list *instructions, > > if (redeclaring_per_vertex) { > ir_variable *earlier = > - get_variable_being_redeclared(var, loc, state, > + get_variable_being_redeclared(, loc, state, > true /* > allow_all_redeclarations */); > if (!var_is_gl_id || earlier == NULL) { > _mesa_glsl_error(, state, > -- > 2.11.0 > > ___ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/mesa-dev > ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
[Mesa-dev] [PATCH v2] glsl: fix heap-use-after-free in ast_declarator_list::hir()
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 assign the pointer 'var' to the pointer 'earlier'. This error was detected by Address Sanitizer. v2: * Pointer-to-pointer assignment (Bartosz Tomczyk) Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99677 Signed-off-by: Samuel Iglesias Gonsálvez--- Another possibility is to use reference-to-pointer but it is a C++ thing. IIRC, we agreed on avoiding C++-specific features to make it easy for C developers, but I have no strong opinion for either option. src/compiler/glsl/ast_to_hir.cpp | 10 ++ 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp index b31b61d1ed6..93ba1d510fa 100644 --- a/src/compiler/glsl/ast_to_hir.cpp +++ b/src/compiler/glsl/ast_to_hir.cpp @@ -3958,10 +3958,12 @@ apply_type_qualifier_to_variable(const struct ast_type_qualifier *qual, * is a redeclaration, \c NULL otherwise. */ static ir_variable * -get_variable_being_redeclared(ir_variable *var, YYLTYPE loc, +get_variable_being_redeclared(ir_variable **var_pointer, YYLTYPE loc, struct _mesa_glsl_parse_state *state, bool allow_all_redeclarations) { + ir_variable *var = *var_pointer; + /* Check if this declaration is actually a re-declaration, either to * resize an array or add qualifiers to an existing variable. * @@ -3999,7 +4001,7 @@ get_variable_being_redeclared(ir_variable *var, YYLTYPE loc, earlier->type = var->type; delete var; - var = NULL; + *var_pointer = earlier; } else if ((state->ARB_fragment_coord_conventions_enable || state->is_version(150, 0)) && strcmp(var->name, "gl_FragCoord") == 0 @@ -5207,7 +5209,7 @@ ast_declarator_list::hir(exec_list *instructions, bool var_is_gl_id = is_gl_identifier(var->name); ir_variable *earlier = - get_variable_being_redeclared(var, decl->get_location(), state, + get_variable_being_redeclared(, decl->get_location(), state, false /* allow_all_redeclarations */); if (earlier != NULL) { if (var_is_gl_id && @@ -7873,7 +7875,7 @@ ast_interface_block::hir(exec_list *instructions, if (redeclaring_per_vertex) { ir_variable *earlier = - get_variable_being_redeclared(var, loc, state, + get_variable_being_redeclared(, loc, state, true /* allow_all_redeclarations */); if (!var_is_gl_id || earlier == NULL) { _mesa_glsl_error(, state, -- 2.11.0 ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev