| Summary: | -Wanalyzer-write-to-const and -Wanalyzer-write-to-string-literal should respect attribute((access, write) | ||
|---|---|---|---|
| Product: | gcc | Reporter: | David Malcolm <dmalcolm> |
| Component: | analyzer | Assignee: | David Malcolm <dmalcolm> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | ||
| Priority: | P3 | ||
| Version: | 12.0 | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | ||
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Description
David Malcolm
2022-03-04 19:57:17 UTC
See also PR analyzer/104860, which covers this for -Wanalyzer-possible-null-argument and -Wanalyzer-null-argument. The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>: https://gcc.gnu.org/g:b6eaf90c64f91553c8002f6ee401785a8bc6f94c commit r12-7595-gb6eaf90c64f91553c8002f6ee401785a8bc6f94c Author: David Malcolm <dmalcolm@redhat.com> Date: Thu Mar 10 09:04:03 2022 -0500 analyzer: check for writes to consts via access attr [PR104793] This patch extends: -Wanalyzer-write-to-const -Wanalyzer-write-to-string-literal so that they will check for __attribute__ ((access, ....) on calls to externally-defined functions, and complain about read-only regions pointed to by arguments marked with a "write_only" or "read_write" attribute. gcc/analyzer/ChangeLog: PR analyzer/104793 * region-model.cc (region_model::check_external_function_for_access_attr): New. (region_model::handle_unrecognized_call): Call it. * region-model.h (region_model::check_external_function_for_access_attr): New decl. (region_model::handle_unrecognized_call): New decl. gcc/testsuite/ChangeLog: PR analyzer/104793 * gcc.dg/analyzer/write-to-const-2.c: New test. * gcc.dg/analyzer/write-to-function-1.c: New test. * gcc.dg/analyzer/write-to-string-literal-2.c: New test. * gcc.dg/analyzer/write-to-string-literal-3.c: New test. * gcc.dg/analyzer/write-to-string-literal-4.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:c65d3c7f9dade18826d1a28d71b98c7cdc3e4300 commit r12-7596-gc65d3c7f9dade18826d1a28d71b98c7cdc3e4300 Author: David Malcolm <dmalcolm@redhat.com> Date: Thu Mar 10 09:09:40 2022 -0500 analyzer: add notes to write-to-const/string from access attr [PR104793] The previous patch extended -Wanalyzer-write-to-const -Wanalyzer-write-to-string-literal to make use of __attribute__ ((access, ....), but the results could be inscrutable. This patch adds notes to such diagnostics to give the user a reason for why the analyzer is complaining. Example output: test.c: In function 'main': test.c:15:13: warning: write to string literal [-Wanalyzer-write-to-string-literal] 15 | if (getrandom((char *)test, sizeof(buf), GRND_RANDOM)) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 'main': event 1 | | 15 | if (getrandom((char *)test, sizeof(buf), GRND_RANDOM)) | | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (1) write to string literal here | test.c:3:5: note: parameter 1 of 'getrandom' marked with attribute 'access (write_only, 1, 2)' 3 | int getrandom (void *__buffer, size_t __length, | ^~~~~~~~~ Unfortunately we don't have location information for the attributes themselves, just the function declaration, and there doesn't seem to be a good way of getting at the location of the individual parameters from the middle end (the C and C++ FEs both have get_fndecl_argument_location, but the implementations are different). gcc/analyzer/ChangeLog: PR analyzer/104793 * analyzer.h (class pending_note): New forward decl. * diagnostic-manager.cc (saved_diagnostic::saved_diagnostic): Initialize m_notes. (saved_diagnostic::operator==): Compare m_notes. (saved_diagnostic::add_note): New. (saved_diagnostic::emit_any_notes): New. (diagnostic_manager::add_note): New. (diagnostic_manager::emit_saved_diagnostic): Call emit_any_notes after emitting the warning. * diagnostic-manager.h (saved_diagnostic::add_note): New decl. (saved_diagnostic::emit_any_notes): New decl. (saved_diagnostic::m_notes): New field. (diagnostic_manager::add_note): New decl. * engine.cc (impl_region_model_context::add_note): New. * exploded-graph.h (impl_region_model_context::add_note): New decl. * pending-diagnostic.h (class pending_note): New. (class pending_note_subclass): New template. * region-model.cc (class reason_attr_access): New. (check_external_function_for_access_attr): Add class annotating_ctxt and use it when checking region. (noop_region_model_context::add_note): New. * region-model.h (region_model_context::add_note): New vfunc. (noop_region_model_context::add_note): New decl. (class region_model_context_decorator): New. (class note_adding_context): New. gcc/testsuite/ChangeLog: PR analyzer/104793 * gcc.dg/analyzer/write-to-const-2.c: Add dg-message directives for expected notes. * gcc.dg/analyzer/write-to-function-1.c: Likewise. * gcc.dg/analyzer/write-to-string-literal-2.c: Likewise. * gcc.dg/analyzer/write-to-string-literal-3.c: Likewise. * gcc.dg/analyzer/write-to-string-literal-4.c: Likewise. * gcc.dg/analyzer/write-to-string-literal-5.c: New test. Signed-off-by: David Malcolm <dmalcolm@redhat.com> Should be fixed by the above commits. |