From e802bff69ee74983215d0c2b7e213fca6d68a97d Mon Sep 17 00:00:00 2001 From: Danylo Piliaiev Date: Tue, 18 Aug 2020 10:41:31 +0300 Subject: [PATCH] glsl: Eliminate out-of-bounds triop_vector_insert MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says: "In the subsections described above for array, vector, matrix and structure accesses, any out-of-bounds access produced undefined behavior.... Out-of-bounds writes may be discarded or overwrite other variables of the active program." Fixes crashes when dereferencing gl_ClipDistance and gl_TessLevel*, e.g: int index = -1; gl_ClipDistance[index] = -1; When LowerCombinedClipCullDistance is true. CC: Signed-off-by: Danylo Piliaiev Reviewed-by: Eric Anholt Reviewed-by: Marcin Ślusarz Part-of: --- src/compiler/glsl/lower_vector_insert.cpp | 33 ++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/src/compiler/glsl/lower_vector_insert.cpp b/src/compiler/glsl/lower_vector_insert.cpp index ceaa5887c8a..81ef0491c3a 100644 --- a/src/compiler/glsl/lower_vector_insert.cpp +++ b/src/compiler/glsl/lower_vector_insert.cpp @@ -32,7 +32,8 @@ namespace { class vector_insert_visitor : public ir_rvalue_visitor { public: vector_insert_visitor(bool lower_nonconstant_index) - : progress(false), lower_nonconstant_index(lower_nonconstant_index) + : progress(false), lower_nonconstant_index(lower_nonconstant_index), + remove_assignment(false) { factory.instructions = &factory_instructions; } @@ -43,11 +44,13 @@ public: } virtual void handle_rvalue(ir_rvalue **rv); + virtual ir_visitor_status visit_leave(ir_assignment *expr); ir_factory factory; exec_list factory_instructions; bool progress; bool lower_nonconstant_index; + bool remove_assignment; }; } /* anonymous namespace */ @@ -68,6 +71,21 @@ vector_insert_visitor::handle_rvalue(ir_rvalue **rv) ir_constant *const idx = expr->operands[2]->constant_expression_value(factory.mem_ctx); if (idx != NULL) { + unsigned index = idx->value.u[0]; + + if (index >= expr->operands[0]->type->vector_elements) { + /* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says: + * + * In the subsections described above for array, vector, matrix and + * structure accesses, any out-of-bounds access produced undefined + * behavior.... Out-of-bounds writes may be discarded or overwrite + * other variables of the active program. + */ + this->remove_assignment = true; + this->progress = true; + return; + } + /* Replace (vector_insert (vec) (scalar) (index)) with a dereference of * a new temporary. The new temporary gets assigned as * @@ -136,6 +154,19 @@ vector_insert_visitor::handle_rvalue(ir_rvalue **rv) base_ir->insert_before(factory.instructions); } +ir_visitor_status +vector_insert_visitor::visit_leave(ir_assignment *ir) +{ + ir_rvalue_visitor::visit_leave(ir); + + if (this->remove_assignment) { + ir->remove(); + this->remove_assignment = false; + } + + return visit_continue; +} + bool lower_vector_insert(exec_list *instructions, bool lower_nonconstant_index) { -- 2.30.2