https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106626
--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by David Malcolm <dmalc...@gcc.gnu.org>: https://gcc.gnu.org/g:0e466e978c728697f18c67c4eace9ba4633f9ef5 commit r14-2029-g0e466e978c728697f18c67c4eace9ba4633f9ef5 Author: David Malcolm <dmalc...@redhat.com> Date: Wed Jun 21 21:49:00 2023 -0400 analyzer: add text-art visualizations of out-of-bounds accesses [PR106626] This patch extends -Wanalyzer-out-of-bounds so that, where possible, it will emit a text art diagram visualizing the spatial relationship between (a) the memory region that the analyzer predicts would be accessed, versus (b) the range of memory that is valid to access - whether they overlap, are touching, are close or far apart; which one is before or after in memory, the relative sizes involved, the direction of the access (read vs write), and, in some cases, the values of data involved. This diagram can be suppressed using -fdiagnostics-text-art-charset=none. For example, given: int32_t arr[10]; int32_t int_arr_read_element_before_start_far(void) { return arr[-100]; } it emits: demo-1.c: In function âint_arr_read_element_before_start_farâ: demo-1.c:7:13: warning: buffer under-read [CWE-127] [-Wanalyzer-out-of-bounds] 7 | return arr[-100]; | ~~~^~~~~~ âint_arr_read_element_before_start_farâ: event 1 | | 7 | return arr[-100]; | | ~~~^~~~~~ | | | | | (1) out-of-bounds read from byte -400 till byte -397 but âarrâ starts at byte 0 | demo-1.c:7:13: note: valid subscripts for âarrâ are â[0]â to â[9]â âââââââââââââââââââââââââââââ âread of âint32_tâ (4 bytes)â âââââââââââââââââââââââââââââ ^ â â âââââââââââââââââââââââââââââ ââââââââââ¬âââââââââ¬ââââââââââ â â â [0] â ... â [9] â â before valid range â ââââââââââ´âââââââââ´âââââââââ⤠â â ââarrâ (type: âint32_t[10]â)â âââââââââââââââââââââââââââââ âââââââââââââââââââââââââââââ âââââââââââââââ¬ââââââââââââââ¤âââââââ¬âââââââ¤âââââââââââââââ¬âââââââââââââ⤠â â â ââââââââââââââ´ââââââââââââ® ââââââ´âââââ® âââââââââ´âââââââ® ââ ï¸ under-read of 4 bytesâ â396 bytesâ âsize: 40 bytesâ â°ââââââââââââââââââââââââ⯠â°âââââââââ⯠â°ââââââââââââââ⯠and given: #include <string.h> void test_non_ascii () { char buf[5]; strcpy (buf, "æååã"); } it emits: demo-2.c: In function âtest_non_asciiâ: demo-2.c:7:3: warning: stack-based buffer overflow [CWE-121] [-Wanalyzer-out-of-bounds] 7 | strcpy (buf, "æååã"); | ^~~~~~~~~~~~~~~~~~~~~~~~ âtest_non_asciiâ: events 1-2 | | 6 | char buf[5]; | | ^~~ | | | | | (1) capacity: 5 bytes | 7 | strcpy (buf, "æååã"); | | ~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | (2) out-of-bounds write from byte 5 till byte 12 but âbufâ ends at byte 5 | demo-2.c:7:3: note: write of 8 bytes to beyond the end of âbufâ 7 | strcpy (buf, "æååã"); | ^~~~~~~~~~~~~~~~~~~~~~~~ demo-2.c:7:3: note: valid subscripts for âbufâ are â[0]â to â[4]â âââââââ¬ââââââ¬ââââââ¬âââââ¬âââââââââââ¬âââââ¬âââââ¬âââââ¬âââââ¬âââââ¬âââââ¬âââââââ â [0] â [1] â [2] â[3] â[4] ââ[5] â[6] â[7] â[8] â[9] â[10]â[11]â [12] â âââââââ¼ââââââ¼ââââââ¼âââââ¼âââââ¤ââââââ¼âââââ¼âââââ¼âââââ¼âââââ¼âââââ¼âââââ¼ââââââ⤠â0xe6 â0x96 â0x87 â0xe5â0xadââ0x97â0xe5â0x8câ0x96â0xe3â0x81â0x91â 0x00 â âââââââ´ââââââ´ââââââ¼âââââ´âââââ´â´âââââ¼âââââ´âââââ´âââââ¼âââââ´âââââ´âââââ¼ââââââ⤠â U+6587 â U+5b57 â U+5316 â U+3051 âU+0000â âââââââââââââââââââ¼ââââââââââââââââ¼âââââââââââââââ¼âââââââââââââââ¼ââââââ⤠â æ â å â å â ã â NUL â âââââââââââââââââââ´ââââââââââââââââ´âââââââââââââââ´âââââââââââââââ´ââââââ⤠â string literal (type: âchar[13]â) â ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ â â â â â â â â â â â â â â â â â â â â â â â â â â v v v v v v v v v v v v v âââââââ¬âââââââââââââââââ¬ââââââââââââââââââââââââââââââââââââââââââââââââ â [0] â ... â[4] ââ â âââââââ´âââââââââââââââââ´âââââ¤â after valid range â â âbufâ (type: âchar[5]â) ââ â ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ âââââââââââââââ¬ââââââââââââââ¤ââââââââââââââââââââââ¬ââââââââââââââââââââ⤠â â ââââââââââ´âââââââââ® âââââââââââââ´âââââââââââ® âcapacity: 5 bytesâ ââ ï¸ overflow of 8 bytesâ â°âââââââââââââââââ⯠â°ââââââââââââââââââââââ⯠showing that the overflow occurs partway through the UTF-8 encoding of the U+5b57 code point. There are lots more examples in the test suite. It doesn't show up in this email, but the above diagrams are colorized to constrast the valid and invalid access ranges. gcc/ChangeLog: PR analyzer/106626 * Makefile.in (ANALYZER_OBJS): Add analyzer/access-diagram.o. * doc/invoke.texi (Wanalyzer-out-of-bounds): Add description of text art. (fanalyzer-debug-text-art): New. gcc/analyzer/ChangeLog: PR analyzer/106626 * access-diagram.cc: New file. * access-diagram.h: New file. * analyzer.h (class region_offset): Add default ctor. (region_offset::make_byte_offset): New decl. (region_offset::concrete_p): New. (region_offset::get_concrete_byte_offset): New. (region_offset::calc_symbolic_bit_offset): New decl. (region_offset::calc_symbolic_byte_offset): New decl. (region_offset::dump_to_pp): New decl. (region_offset::dump): New decl. (operator<, operator<=, operator>, operator>=): New decls for region_offset. * analyzer.opt (-param=analyzer-text-art-string-ellipsis-threshold=): New. (-param=analyzer-text-art-string-ellipsis-head-len=): New. (-param=analyzer-text-art-string-ellipsis-tail-len=): New. (-param=analyzer-text-art-ideal-canvas-width=): New. (fanalyzer-debug-text-art): New. * bounds-checking.cc: Include "intl.h", "diagnostic-diagram.h", and "analyzer/access-diagram.h". (class out_of_bounds::oob_region_creation_event_capacity): New. (out_of_bounds::out_of_bounds): Add "model" and "sval_hint" params. (out_of_bounds::mark_interesting_stuff): Use the base region. (out_of_bounds::add_region_creation_events): Use oob_region_creation_event_capacity. (out_of_bounds::get_dir): New pure vfunc. (out_of_bounds::maybe_show_notes): New. (out_of_bounds::maybe_show_diagram): New. (out_of_bounds::make_access_diagram): New. (out_of_bounds::m_model): New field. (out_of_bounds::m_sval_hint): New field. (out_of_bounds::m_region_creation_event_id): New field. (concrete_out_of_bounds::concrete_out_of_bounds): Update for new fields. (concrete_past_the_end::concrete_past_the_end): Likewise. (concrete_past_the_end::add_region_creation_events): Use oob_region_creation_event_capacity. (concrete_buffer_overflow::concrete_buffer_overflow): Update for new fields. (concrete_buffer_overflow::emit): Replace call to maybe_describe_array_bounds with maybe_show_notes. (concrete_buffer_overflow::get_dir): New. (concrete_buffer_over_read::concrete_buffer_over_read): Update for new fields. (concrete_buffer_over_read::emit): Replace call to maybe_describe_array_bounds with maybe_show_notes. (concrete_buffer_overflow::get_dir): New. (concrete_buffer_underwrite::concrete_buffer_underwrite): Update for new fields. (concrete_buffer_underwrite::emit): Replace call to maybe_describe_array_bounds with maybe_show_notes. (concrete_buffer_underwrite::get_dir): New. (concrete_buffer_under_read::concrete_buffer_under_read): Update for new fields. (concrete_buffer_under_read::emit): Replace call to maybe_describe_array_bounds with maybe_show_notes. (concrete_buffer_under_read::get_dir): New. (symbolic_past_the_end::symbolic_past_the_end): Update for new fields. (symbolic_buffer_overflow::symbolic_buffer_overflow): Likewise. (symbolic_buffer_overflow::emit): Call maybe_show_notes. (symbolic_buffer_overflow::get_dir): New. (symbolic_buffer_over_read::symbolic_buffer_over_read): Update for new fields. (symbolic_buffer_over_read::emit): Call maybe_show_notes. (symbolic_buffer_over_read::get_dir): New. (region_model::check_symbolic_bounds): Add "sval_hint" param. Pass it and sized_offset_reg to diagnostics. (region_model::check_region_bounds): Add "sval_hint" param, passing it to diagnostics. * diagnostic-manager.cc (diagnostic_manager::emit_saved_diagnostic): Pass logger to pending_diagnostic::emit. * engine.cc: Add logger param to pending_diagnostic::emit implementations. * infinite-recursion.cc: Likewise. * kf-analyzer.cc: Likewise. * kf.cc: Likewise. Add nullptr for new param of check_region_for_write. * pending-diagnostic.h: Likewise in decl. * region-model-manager.cc (region_model_manager::get_or_create_int_cst): Convert param from poly_int64 to const poly_wide_int_ref &. (region_model_manager::maybe_fold_binop): Support type being NULL when checking for floating-point types. Check for (X + Y) - X => Y. Be less strict about types when folding associative ops. Check for (X + Y) * CST => (X * CST) + (Y * CST). * region-model-manager.h (region_model_manager::get_or_create_int_cst): Convert param from poly_int64 to const poly_wide_int_ref &. * region-model.cc: Add logger param to pending_diagnostic::emit implementations. (region_model::check_external_function_for_access_attr): Update for new param of check_region_for_write. (region_model::deref_rvalue): Use nullptr rather than NULL. (region_model::get_capacity): Handle RK_STRING. (region_model::check_region_access): Add "sval_hint" param; pass it to check_region_bounds. (region_model::check_region_for_write): Add "sval_hint" param; pass it to check_region_access. (region_model::check_region_for_read): Add NULL for new param to check_region_access. (region_model::set_value): Pass rhs_sval to check_region_for_write. (region_model::get_representative_path_var_1): Handle SK_CONSTANT in the check for infinite recursion. * region-model.h (region_model::check_region_for_write): Add "sval_hint" param. (region_model::check_region_access): Likewise. (region_model::check_symbolic_bounds): Likewise. (region_model::check_region_bounds): Likewise. * region.cc (region_offset::make_byte_offset): New. (region_offset::calc_symbolic_bit_offset): New. (region_offset::calc_symbolic_byte_offset): New. (region_offset::dump_to_pp): New. (region_offset::dump): New. (struct linear_op): New. (operator<, operator<=, operator>, operator>=): New, for region_offset. (region::get_next_offset): New. (region::get_relative_symbolic_offset): Use ptrdiff_type_node. (field_region::get_relative_symbolic_offset): Likewise. (element_region::get_relative_symbolic_offset): Likewise. (bit_range_region::get_relative_symbolic_offset): Likewise. * region.h (region::get_next_offset): New decl. * sm-fd.cc: Add logger param to pending_diagnostic::emit implementations. * sm-file.cc: Likewise. * sm-malloc.cc: Likewise. * sm-pattern-test.cc: Likewise. * sm-sensitive.cc: Likewise. * sm-signal.cc: Likewise. * sm-taint.cc: Likewise. * store.cc (bit_range::contains_p): Allow "out" to be null. * store.h (byte_range::get_start_bit_offset): New. (byte_range::get_next_bit_offset): New. * varargs.cc: Add logger param to pending_diagnostic::emit implementations. gcc/testsuite/ChangeLog: PR analyzer/106626 * gcc.dg/analyzer/data-model-1.c (test_16): Update for out-of-bounds working. * gcc.dg/analyzer/out-of-bounds-diagram-1-ascii.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-1-debug.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-1-emoji.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-1-json.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-1-sarif.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-1-unicode.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-10.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-11.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-12.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-13.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-14.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-15.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-2.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-3.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-4.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-5-ascii.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-5-unicode.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-6.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-7.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-8.c: New test. * gcc.dg/analyzer/out-of-bounds-diagram-9.c: New test. * gcc.dg/analyzer/pattern-test-2.c: Update expected results. * gcc.dg/analyzer/pr101962.c: Update expected results. * gcc.dg/plugin/analyzer_gil_plugin.c: Add logger param to pending_diagnostic::emit implementations. Signed-off-by: David Malcolm <dmalc...@redhat.com>
