I removed -Wanalyzer-use-of-uninitialized-value in r10-8012-g78b9783774bfd3540f38f5b1e3c7fc9f719653d7 as it had too many false positives: https://gcc.gnu.org/pipermail/gcc-patches/2020-April/544726.html This is a tracker bug, for keeping track of what needs fixing in order to reimplement it.
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>: https://gcc.gnu.org/g:e61ffa201403e3814a43b176883e176716b1492f commit r12-1931-ge61ffa201403e3814a43b176883e176716b1492f Author: David Malcolm <dmalcolm@redhat.com> Date: Wed Jun 30 09:39:04 2021 -0400 analyzer: eliminate enum binding_key [PR95006] I rewrote the way the analyzer's region_model tracks the state of memory in GCC 11 (in 808f4dfeb3a95f50f15e71148e5c1067f90a126d), which introduced a store with a binding_map class, mapping binding keys to symbolic values. The GCC 11 implementation of binding keys has an enum binding_kind, which can be "default" vs "direct"; the idea being that direct bindings take priority over default bindings, where the latter could be used to represent e.g. a zero-fill of a buffer, and the former expresses those subregions that have since been touched. This doesn't work well: it doesn't express the idea of filling different subregions with different values, or a memset that only touches part of a buffer, leading to numerous XFAILs in the memset test cases (and elsewhere). As preparatory work towards tracking uninitialized values, this patch eliminates the enum binding_kind, so that all bindings have equal weight; the order in which they happen is all that matters. If a write happens which partially overwrites an existing binding, the new code can partially overwrite a binding, potentially punching a hole so that an existing binding is split into two parts. The patch adds some new classes: - a new "bits_within_svalue" symbolic value to support extracting parts of an existing value when its binding is partially clobbered - a new "repeated_svalue" symbolic value to better express filling a region with repeated copies of a symbolic value (e.g. constant zero) - a new "sized_region" region to express accessing a subregion with a symbolic size in bytes and it rewrites e.g. how memset is implemented, so that we can precisely track which bits in a region have not been touched. That said, the patch doesn't actually implement "uninitialized" values; I'm saving that for a followup. gcc/analyzer/ChangeLog: PR analyzer/95006 * analyzer.h (class repeated_svalue): New forward decl. (class bits_within_svalue): New forward decl. (class sized_region): New forward decl. (get_field_at_bit_offset): New forward decl. * engine.cc (exploded_graph::get_or_create_node): Validate the merged state. (exploded_graph::maybe_process_run_of_before_supernode_enodes): Validate the states at each stage. * program-state.cc (program_state::validate): Validate m_region_model. * region-model-impl-calls.cc (region_model::impl_call_memset): Replace special-case logic for handling constant sizes with a call to fill_region of a sized_region with the given fill value. * region-model-manager.cc (maybe_undo_optimize_bit_field_compare): Drop DK_direct. (region_model_manager::maybe_fold_sub_svalue): Fold element-based subregions of an initial value into initial values of an element. Fold subvalues of repeated svalues. (region_model_manager::maybe_fold_repeated_svalue): New. (region_model_manager::get_or_create_repeated_svalue): New. (get_bit_range_for_field): New. (get_byte_range_for_field): New. (get_field_at_byte_range): New. (region_model_manager::maybe_fold_bits_within_svalue): New. (region_model_manager::get_or_create_bits_within): New. (region_model_manager::get_sized_region): New. (region_model_manager::log_stats): Update for addition of m_repeated_values_map, m_bits_within_values_map, and m_sized_regions. * region-model.cc (region_model::validate): New. (region_model::on_assignment): Drop enum binding_kind. (region_model::get_initial_value_for_global): Likewise. (region_model::get_rvalue_for_bits): Replace body with call to get_or_create_bits_within. (region_model::get_capacity): Handle RK_SIZED. (region_model::set_value): Drop enum binding_kind. (region_model::fill_region): New. (region_model::get_representative_path_var_1): Handle RK_SIZED. * region-model.h (visitor::visit_repeated_svalue): New. (visitor::visit_bits_within_svalue): New. (region_model_manager::get_or_create_repeated_svalue): New decl. (region_model_manager::get_or_create_bits_within): New decl. (region_model_manager::get_sized_region): New decl. (region_model_manager::maybe_fold_repeated_svalue): New decl. (region_model_manager::maybe_fold_bits_within_svalue): New decl. (region_model_manager::repeated_values_map_t): New typedef. (region_model_manager::m_repeated_values_map): New field. (region_model_manager::bits_within_values_map_t): New typedef. (region_model_manager::m_bits_within_values_map): New field. (region_model_manager::m_sized_regions): New field. (region_model::fill_region): New decl. * region.cc (region::get_base_region): Handle RK_SIZED. (region::base_region_p): Likewise. (region::get_byte_size_sval): New. (get_field_at_bit_offset): Make non-static. (region::calc_offset): Move implementation of cases to get_relative_concrete_offset vfunc implementations. Handle RK_SIZED. (region::get_relative_concrete_offset): New. (decl_region::get_svalue_for_initializer): Drop enum binding_kind. (field_region::get_relative_concrete_offset): New, from region::calc_offset. (element_region::get_relative_concrete_offset): Likewise. (offset_region::get_relative_concrete_offset): Likewise. (sized_region::accept): New. (sized_region::dump_to_pp): New. (sized_region::get_byte_size): New. (sized_region::get_bit_size): New. * region.h (enum region_kind): Add RK_SIZED. (region::dyn_cast_sized_region): New. (region::get_byte_size): Make virtual. (region::get_bit_size): Likewise. (region::get_byte_size_sval): New decl. (region::get_relative_concrete_offset): New decl. (field_region::get_relative_concrete_offset): New decl. (element_region::get_relative_concrete_offset): Likewise. (offset_region::get_relative_concrete_offset): Likewise. (class sized_region): New. * store.cc (binding_kind_to_string): Delete. (binding_key::make): Drop enum binding_kind. (binding_key::dump_to_pp): Delete. (binding_key::cmp_ptrs): Drop enum binding_kind. (bit_range::contains_p): New. (byte_range::dump): New. (byte_range::contains_p): New. (byte_range::cmp): New. (concrete_binding::dump_to_pp): Drop enum binding_kind. (concrete_binding::cmp_ptr_ptr): Likewise. (symbolic_binding::dump_to_pp): Likewise. (symbolic_binding::cmp_ptr_ptr): Likewise. (binding_map::apply_ctor_val_to_range): Likewise. (binding_map::apply_ctor_pair_to_child_region): Likewise. (binding_map::get_overlapping_bindings): New. (binding_map::remove_overlapping_bindings): New. (binding_cluster::validate): New. (binding_cluster::bind): Drop enum binding_kind. (binding_cluster::bind_compound_sval): Likewise. (binding_cluster::purge_region): Likewise. (binding_cluster::zero_fill_region): Reimplement in terms of... (binding_cluster::fill_region): New. (binding_cluster::mark_region_as_unknown): Drop enum binding_kind. (binding_cluster::get_binding): Likewise. (binding_cluster::get_binding_recursive): Likewise. (binding_cluster::get_any_binding): Likewise. (binding_cluster::maybe_get_compound_binding): Reimplement. (binding_cluster::get_overlapping_bindings): Delete. (binding_cluster::remove_overlapping_bindings): Reimplement in terms of binding_map::remove_overlapping_bindings. (binding_cluster::can_merge_p): Update for removal of enum binding_kind. (binding_cluster::on_unknown_fncall): Drop enum binding_kind. (binding_cluster::maybe_get_simple_value): Likewise. (store_manager::get_concrete_binding): Likewise. (store_manager::get_symbolic_binding): Likewise. (store::validate): New. (store::set_value): Drop enum binding_kind. (store::zero_fill_region): Reimplement in terms of... (store::fill_region): New. (selftest::test_binding_key_overlap): Drop enum binding_kind. * store.h (enum binding_kind): Delete. (binding_kind_to_string): Delete decl. (binding_key::make): Drop enum binding_kind. (binding_key::dump_to_pp): Make pure virtual. (binding_key::get_kind): Delete. (binding_key::mark_deleted): Delete. (binding_key::mark_empty): Delete. (binding_key::is_deleted): Delete. (binding_key::is_empty): Delete. (binding_key::binding_key): Delete. (binding_key::impl_hash): Delete. (binding_key::impl_eq): Delete. (binding_key::m_kind): Delete. (bit_range::get_last_bit_offset): New. (bit_range::contains_p): New. (byte_range::contains_p): New. (byte_range::operator==): New. (byte_range::get_start_byte_offset): New. (byte_range::get_next_byte_offset): New. (byte_range::get_last_byte_offset): New. (byte_range::as_bit_range): New. (byte_range::cmp): New. (concrete_binding::concrete_binding): Drop enum binding_kind. (concrete_binding::hash): Likewise. (concrete_binding::operator==): Likewise. (concrete_binding::mark_deleted): New. (concrete_binding::mark_empty): New. (concrete_binding::is_deleted): New. (concrete_binding::is_empty): New. (default_hash_traits<ana::concrete_binding>::empty_zero_p): Make false. (symbolic_binding::symbolic_binding): Drop enum binding_kind. (symbolic_binding::hash): Likewise. (symbolic_binding::operator==): Likewise. (symbolic_binding::mark_deleted): New. (symbolic_binding::mark_empty): New. (symbolic_binding::is_deleted): New. (symbolic_binding::is_empty): New. (binding_map::remove_overlapping_bindings): New decl. (binding_map::get_overlapping_bindings): New decl. (binding_cluster::validate): New decl. (binding_cluster::bind): Drop enum binding_kind. (binding_cluster::fill_region): New decl. (binding_cluster::get_binding): Drop enum binding_kind. (binding_cluster::get_binding_recursive): Likewise. (binding_cluster::get_overlapping_bindings): Delete. (store::validate): New decl. (store::set_value): Drop enum binding_kind. (store::fill_region): New decl. (store_manager::get_concrete_binding): Drop enum binding_kind. (store_manager::get_symbolic_binding): Likewise. * svalue.cc (svalue::cmp_ptr): Handle SK_REPEATED and SK_BITS_WITHIN. (svalue::extract_bit_range): New. (svalue::maybe_fold_bits_within): New. (constant_svalue::maybe_fold_bits_within): New. (unknown_svalue::maybe_fold_bits_within): New. (unaryop_svalue::maybe_fold_bits_within): New. (repeated_svalue::repeated_svalue): New. (repeated_svalue::dump_to_pp): New. (repeated_svalue::accept): New. (repeated_svalue::all_zeroes_p): New. (repeated_svalue::maybe_fold_bits_within): New. (bits_within_svalue::bits_within_svalue): New. (bits_within_svalue::dump_to_pp): New. (bits_within_svalue::maybe_fold_bits_within): New. (bits_within_svalue::accept): New. (bits_within_svalue::implicitly_live_p): New. (compound_svalue::maybe_fold_bits_within): New. * svalue.h (enum svalue_kind): Add SK_REPEATED and SK_BITS_WITHIN. (svalue::dyn_cast_repeated_svalue): New. (svalue::dyn_cast_bits_within_svalue): New. (svalue::extract_bit_range): New decl. (svalue::maybe_fold_bits_within): New vfunc decl. (region_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (region_svalue::key_t::is_empty): Likewise. (default_hash_traits<region_svalue::key_t>::empty_zero_p): Make false. (constant_svalue::maybe_fold_bits_within): New. (unknown_svalue::maybe_fold_bits_within): New. (poisoned_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (poisoned_svalue::key_t::is_empty): Likewise. (default_hash_traits<poisoned_svalue::key_t>::empty_zero_p): Make false. (setjmp_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (setjmp_svalue::key_t::is_empty): Likewise. (default_hash_traits<setjmp_svalue::key_t>::empty_zero_p): Make false. (unaryop_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (unaryop_svalue::key_t::is_empty): Likewise. (unaryop_svalue::maybe_fold_bits_within): New. (default_hash_traits<unaryop_svalue::key_t>::empty_zero_p): Make false. (binop_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (binop_svalue::key_t::is_empty): Likewise. (default_hash_traits<binop_svalue::key_t>::empty_zero_p): Make false. (sub_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (sub_svalue::key_t::is_empty): Likewise. (default_hash_traits<sub_svalue::key_t>::empty_zero_p): Make false. (class repeated_svalue): New. (is_a_helper <const repeated_svalue *>::test): New. (struct default_hash_traits<repeated_svalue::key_t>): New. (class bits_within_svalue): New. (is_a_helper <const bits_within_svalue *>::test): New. (struct default_hash_traits<bits_within_svalue::key_t>): New. (widening_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (widening_svalue::key_t::is_empty): Likewise. (default_hash_traits<widening_svalue::key_t>::empty_zero_p): Make false. (compound_svalue::key_t::mark_empty): Use 2 rather than NULL_TREE. (compound_svalue::key_t::is_empty): Likewise. (compound_svalue::maybe_fold_bits_within): New. (default_hash_traits<compound_svalue::key_t>::empty_zero_p): Make false. gcc/testsuite/ChangeLog: PR analyzer/95006 * gcc.dg/analyzer/clobbers-1.c: New test. * gcc.dg/analyzer/clobbers-2.c: New test. * gcc.dg/analyzer/data-model-1.c (test_26): Mark xfail as fixed. (test_28): Likewise. (test_52): Likewise. Add coverage for end of buffer. * gcc.dg/analyzer/explode-1.c: Add leak warning. * gcc.dg/analyzer/memset-1.c (test_3): Mark xfail as fixed. (test_4): Use char. Mark xfail as fixed. (test_6b): New. (test_7): Mark xfail as fixed. Add coverage for start of buffer. (test_8): New. (test_9): New. * gcc.dg/analyzer/memset-CVE-2017-18549-1.c: New test. * gcc.dg/analyzer/symbolic-8.c: New test. Signed-off-by: David Malcolm <dmalcolm@redhat.com>
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>: https://gcc.gnu.org/g:33255ad3ac14e3953750fe0f2d82b901c2852ff6 commit r12-2337-g33255ad3ac14e3953750fe0f2d82b901c2852ff6 Author: David Malcolm <dmalcolm@redhat.com> Date: Thu Jul 15 15:07:07 2021 -0400 analyzer: reimplement -Wanalyzer-use-of-uninitialized-value [PR95006 et al] The initial gcc 10 era commit of the analyzer (in 757bf1dff5e8cee34c0a75d06140ca972bfecfa7) had an implementation of -Wanalyzer-use-of-uninitialized-value, but was sufficiently buggy that I removed it in 78b9783774bfd3540f38f5b1e3c7fc9f719653d7 before the release of gcc 10.1 This patch reintroduces the warning, heavily rewritten, with (I hope) a less buggy implementation this time, for GCC 12. gcc/analyzer/ChangeLog: PR analyzer/95006 PR analyzer/94713 PR analyzer/94714 * analyzer.cc (maybe_reconstruct_from_def_stmt): Split out GIMPLE_ASSIGN case into... (get_diagnostic_tree_for_gassign_1): New. (get_diagnostic_tree_for_gassign): New. * analyzer.h (get_diagnostic_tree_for_gassign): New decl. * analyzer.opt (Wanalyzer-write-to-string-literal): New. * constraint-manager.cc (class svalue_purger): New. (constraint_manager::purge_state_involving): New. * constraint-manager.h (constraint_manager::purge_state_involving): New. * diagnostic-manager.cc (saved_diagnostic::supercedes_p): New. (dedupe_winners::handle_interactions): New. (diagnostic_manager::emit_saved_diagnostics): Call it. * diagnostic-manager.h (saved_diagnostic::supercedes_p): New decl. * engine.cc (impl_region_model_context::warn): Convert return type to bool. Return false if the diagnostic isn't saved. (impl_region_model_context::purge_state_involving): New. (impl_sm_context::get_state): Use NULL ctxt when querying old rvalue. (impl_sm_context::set_next_state): Use new sval when querying old state. (class dump_path_diagnostic): Move to region-model.cc (exploded_node::on_stmt): Move to on_stmt_pre and on_stmt_post. Remove call to purge_state_involving. (exploded_node::on_stmt_pre): New, based on the above. Move most of it to region_model::on_stmt_pre. (exploded_node::on_stmt_post): Likewise, moving to region_model::on_stmt_post. (class stale_jmp_buf): Fix parent class to use curiously recurring template pattern. (feasibility_state::maybe_update_for_edge): Call on_call_pre and on_call_post on gcalls. * exploded-graph.h (impl_region_model_context::warn): Return bool. (impl_region_model_context::purge_state_involving): New decl. (exploded_node::on_stmt_pre): New decl. (exploded_node::on_stmt_post): New decl. * pending-diagnostic.h (pending_diagnostic::use_of_uninit_p): New. (pending_diagnostic::supercedes_p): New. * program-state.cc (sm_state_map::get_state): Inherit state for conjured_svalue as well as initial_svalue. (sm_state_map::purge_state_involving): Also support SK_CONJURED. * region-model-impl-calls.cc (call_details::get_uncertainty): Handle m_ctxt being NULL. (call_details::get_or_create_conjured_svalue): New. (region_model::impl_call_fgets): New. (region_model::impl_call_fread): New. * region-model-manager.cc (region_model_manager::get_or_create_initial_value): Return an uninitialized poisoned value for regions that can't have initial values. * region-model-reachability.cc (reachable_regions::mark_escaped_clusters): Handle ctxt being NULL. * region-model.cc (region_to_value_map::purge_state_involving): New. (poisoned_value_diagnostic::use_of_uninit_p): New. (poisoned_value_diagnostic::emit): Handle POISON_KIND_UNINIT. (poisoned_value_diagnostic::describe_final_event): Likewise. (region_model::check_for_poison): New. (region_model::on_assignment): Call it. (class dump_path_diagnostic): Move here from engine.cc. (region_model::on_stmt_pre): New, based on exploded_node::on_stmt. (region_model::on_call_pre): Move the setting of the LHS to a conjured svalue to before the checks for specific functions. Handle "fgets", "fgets_unlocked", and "fread". (region_model::purge_state_involving): New. (region_model::handle_unrecognized_call): Handle ctxt being NULL. (region_model::get_rvalue): Call check_for_poison. (selftest::test_stack_frames): Use NULL for context when getting uninitialized rvalue. (selftest::test_alloca): Likewise. * region-model.h (region_to_value_map::purge_state_involving): New decl. (call_details::get_or_create_conjured_svalue): New decl. (region_model::on_stmt_pre): New decl. (region_model::purge_state_involving): New decl. (region_model::impl_call_fgets): New decl. (region_model::impl_call_fread): New decl. (region_model::check_for_poison): New decl. (region_model_context::warn): Return bool. (region_model_context::purge_state_involving): New. (noop_region_model_context::warn): Return bool. (noop_region_model_context::purge_state_involving): New. (test_region_model_context:: warn): Return bool. * region.cc (region::get_memory_space): New. (region::can_have_initial_svalue_p): New. (region::involves_p): New. * region.h (enum memory_space): New. (region::get_memory_space): New decl. (region::can_have_initial_svalue_p): New decl. (region::involves_p): New decl. * sm-malloc.cc (use_after_free::supercedes_p): New. * store.cc (binding_cluster::purge_state_involving): New. (store::purge_state_involving): New. * store.h (class symbolic_binding): New forward decl. (binding_key::dyn_cast_symbolic_binding): New. (symbolic_binding::dyn_cast_symbolic_binding): New. (binding_cluster::purge_state_involving): New. (store::purge_state_involving): New. * svalue.cc (svalue::can_merge_p): Reject attempts to merge poisoned svalues with other svalues, so that we identify paths in which a variable is conditionally uninitialized. (involvement_visitor::visit_conjured_svalue): New. (svalue::involves_p): Also handle SK_CONJURED. (poison_kind_to_str): Handle POISON_KIND_UNINIT. (poisoned_svalue::maybe_fold_bits_within): New. * svalue.h (enum poison_kind): Add POISON_KIND_UNINIT. (poisoned_svalue::maybe_fold_bits_within): New decl. gcc/ChangeLog: PR analyzer/95006 PR analyzer/94713 PR analyzer/94714 * doc/invoke.texi: Add -Wanalyzer-use-of-uninitialized-value. gcc/testsuite/ChangeLog: PR analyzer/95006 PR analyzer/94713 PR analyzer/94714 * g++.dg/analyzer/pr93212.C: Update location of warning. * g++.dg/analyzer/pr94011.C: Add -Wno-analyzer-use-of-uninitialized-value. * g++.dg/analyzer/pr94503.C: Likewise. * gcc.dg/analyzer/clobbers-1.c: Convert "f" from a local to a param to avoid uninitialized warning. * gcc.dg/analyzer/data-model-1.c (test_12): Add test for uninitialized value on result of alloca. (test_12a): Add expected warning. (test_12c): Likewise. (test_19): Likewise. (test_29b): Likewise. (test_29c): Likewise. (test_37): Remove xfail. (test_37a): Likewise. * gcc.dg/analyzer/data-model-20.c: Add warning about leak. * gcc.dg/analyzer/explode-2.c: Remove params; add -Wno-analyzer-too-complex, -Wno-analyzer-malloc-leak, and xfails. Initialize the locals. * gcc.dg/analyzer/explode-2a.c: Initialize the locals. Add expected leak. * gcc.dg/analyzer/fgets-1.c: New test. * gcc.dg/analyzer/fread-1.c: New test. * gcc.dg/analyzer/malloc-1.c (test_16): Add expected warning. (test_40): Likewise. * gcc.dg/analyzer/memset-CVE-2017-18549-1.c: Check for uninitialized padding. * gcc.dg/analyzer/pr93355-localealias-feasibility.c (fread): New decl. (read_alias_file): Call it. * gcc.dg/analyzer/pr94047.c: Add expected warnings. * gcc.dg/analyzer/pr94851-2.c: Likewise. * gcc.dg/analyzer/pr96841.c: Convert local to a param. * gcc.dg/analyzer/pr98628.c: Likewise. * gcc.dg/analyzer/pr99042.c: Updated expected location of leak diagnostics. * gcc.dg/analyzer/symbolic-1.c: Add expected warnings. * gcc.dg/analyzer/symbolic-7.c: Likewise. * gcc.dg/analyzer/torture/pr93649.c: Add expected warning. Skip with -fno-fat-lto-objects. * gcc.dg/analyzer/uninit-1.c: New test. * gcc.dg/analyzer/uninit-2.c: New test. * gcc.dg/analyzer/uninit-3.c: New test. * gcc.dg/analyzer/uninit-4.c: New test. * gcc.dg/analyzer/uninit-pr94713.c: New test. * gcc.dg/analyzer/uninit-pr94714.c: New test. * gcc.dg/analyzer/use-after-free-2.c: New test. * gcc.dg/analyzer/use-after-free-3.c: New test. * gcc.dg/analyzer/zlib-3.c: Add expected warning. * gcc.dg/analyzer/zlib-6.c: Convert locals to params to avoid uninitialized warnings. Remove xfail. * gcc.dg/analyzer/zlib-6a.c: New test, based on the old version of the above. * gfortran.dg/analyzer/pr97668.f: Add -Wno-analyzer-use-of-uninitialized-value and -Wno-analyzer-too-complex. Signed-off-by: David Malcolm <dmalcolm@redhat.com>
Should be fixed on trunk for gcc 12 by the above patch.