[Bug analyzer/111305] New: GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[Bug analyzer/111305] New: GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[geoffreydgr at icloud dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

            Bug ID: 111305
           Summary: GCC Static Analyzer -Wanalyzer-out-of-bounds FP and
                    ICE problem
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: geoffreydgr at icloud dot com
  Target Milestone: ---

ICE bug when analyzing the folowing program. And there also is a FP report of
out-of-bounds. 

cmd: gcc -O0 -fanalyzer
gcc version: x86-64 gcc (trunk)
see it live:
https://godbolt.org/z/qKxde131e

```
#include <stdio.h>
#include <stdint.h>

struct a {
  uint32_t b;
};
union c {
  int8_t b;
};

int32_t *d( int32_t *j, int32_t k, struct a l) {
  int64_t m[1]= {0};
  for (l.b = 0; l.b <= 0; l.b++) {
    printf("FLAG\n");
    l.b == 12 && m[l.b];
  }
}

```

out:
```
<source>: In function 'd':
<source>:15:19: warning: stack-based buffer over-read [CWE-121]
[-Wanalyzer-out-of-bounds]
   15 |     l.b == 12 && m[l.b];
      |                  ~^~~~~
  'd': events 1-10
    |
    |   12 |   int64_t m[1]= {0};
    |      |           ^
    |      |           |
    |      |           (1) capacity: 8 bytes
    |   13 |   for (l.b = 0; l.b <= 0; l.b++) {
    |      |                 ~~~~~~~~
    |      |                     |
    |      |                     (2) following 'true' branch...
    |      |                     (6) following 'true' branch...
    |   14 |     printf("FLAG\n");
    |      |     ~~~~~~~~~~~~~~~~
    |      |     |
    |      |     (3) ...to here
    |      |     (7) ...to here
    |   15 |     l.b == 12 && m[l.b];
    |      |     ~~~~~~~~~~~~~~~~~~~
    |      |               |   | |
    |      |               |   | (9) ...to here
    |      |               |   (10) read of 8 bytes at offset 'l.b * 8' exceeds
'm'
    |      |               (4) following 'false' branch...
    |      |               (5) ...to here
    |      |               (8) following 'true' branch...
    |
<source>:15:19: note: valid subscripts for 'm' are '[0]' to '[0]'
   15 |     l.b == 12 && m[l.b];
      |                  ~^~~~~
during IPA pass: analyzer
<source>:15:15: internal compiler error: in decompose, at wide-int.h:990
   15 |     l.b == 12 && m[l.b];
      |     ~~~~~~~~~~^~~~~~~~~
0x21af71e internal_error(char const*, ...)
        ???:0
0x9dd814 fancy_abort(char const*, int, char const*)
        ???:0
0x185a343 tree_zero_one_valued_p(tree_node*)
        ???:0
0x214b222 generic_simplify_MULT_EXPR(unsigned int, tree_code, tree_node*,
tree_node*, tree_node*)
        ???:0
0xce1d05 fold_binary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0xce96cd fold_build2_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0x18f3716 generic_simplify_23(unsigned int, tree_node*, tree_node*, tree_node*,
tree_node**, tree_code)
        ???:0
0x186889c generic_simplify_PLUS_EXPR(unsigned int, tree_code, tree_node*,
tree_node*, tree_node*)
        ???:0
0xce1d05 fold_binary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0xce96cd fold_build2_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0x21505bf generic_simplify_MULT_EXPR(unsigned int, tree_code, tree_node*,
tree_node*, tree_node*)
        ???:0
0xce1d05 fold_binary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0xce96cd fold_build2_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0x14d2c3f ana::region_offset::calc_symbolic_bit_offset(ana::region_model
const&) const
        ???:0
0x217faff ana::access_range::get_size(ana::region_model const&,
ana::bit_size_expr*) const
        ???:0
0x218cad3 ana::access_diagram_impl::access_diagram_impl(ana::access_operation
const&, diagnostic_event_id_t, text_art::style_manager&, text_art::theme
const&, ana::logger*)
        ???:0
0x2180abb ana::access_diagram::access_diagram(ana::access_operation const&,
diagnostic_event_id_t, text_art::style_manager&, text_art::theme const&,
ana::logger*)
        ???:0
0x2111f43 ana::symbolic_buffer_over_read::emit(rich_location*, ana::logger*)
        ???:0
0x2139d1e ana::diagnostic_manager::emit_saved_diagnostic(ana::exploded_graph
const&, ana::saved_diagnostic&)
        ???:0
0x213a520 ana::diagnostic_manager::emit_saved_diagnostics(ana::exploded_graph
const&)
        ???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1
```

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-02-26
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
ICE happens with GCC 14
False +ve happens with GCC 13 and 14

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |13.3

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu.org
           Priority|P3                          |P1

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P1                          |P2
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 13.{1,2} has been released with this bug, so P2.

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds FP and ICE problem

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Malcolm <dmalcolm@gcc.gnu.org>:

https://gcc.gnu.org/g:1579394c9ecf3d1f678daa54b835c7fc3b76fb6d

commit r14-9527-g1579394c9ecf3d1f678daa54b835c7fc3b76fb6d
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Mon Mar 18 18:44:34 2024 -0400

    analyzer: fix ICEs due to sloppy types in bounds-checking
[PR110902,PR110928,PR111305,PR111441]

    Various analyzer ICEs in our bugzilla relate to sloppy use of types
    within bounds-checking.

    The bounds-checking code works by comparing symbolic *bit* offsets, and
    we don't have a good user-facing type that can represent such an offset
    (ptrdiff_type_node is for *byte* offsets).

    ana::svalue doesn't enforce valid combinations of types for things like
    binary operations.  When I added the access diagrams for GCC 14, this
    could lead to attempts to generate trees for such svalues, leading to
    trees with invalid combinations of types (e.g. PLUS_EXPR or MULT_EXPR of
    incompatible types), leading to ICEs inside the tree folding logic.

    I tried two approaches to fixing this.

    My first approach was to fix the type-handling throughout the
    bounds-checking code to use correct types, using size_type_node for
    sizes, ptrdiff_type_node for byte offsets, and trying ptrdiff_type_node
    for bit offsets.  I implemented this, and it fixed the crashes, but
    unfortunately it led to:
    (a) numerous false negatives from the bounds-checking code, due to it
    becoming unable to be sure that the accessed offset was beyond the valid
    bounds, due to the expressions involved gaining complicated sets of
    nested casts.
    (b) ugly access diagrams full of nested casts (for capacities, gap
    measurements, etc)

    So my second approach, implemented in this patch, is to accept that we
    don't have a tree type for representing bit offsets.  The patch
    represents bit offsets using "typeless" symbolic values i.e. ones for
    which get_type () is NULL_TREE, and implements enough support for basic
    arithemetic as if these are mathematical integers (albeit ones for which
    concrete values within an expression must fit within a signed wide int).
    Such values can't be converted to tree, so the patch avoids such
    conversions, instead implementing a new svalue::maybe_print_for_user for
    printing them to a pretty_printer.  The patch uses ptrdiff_type_node for
    byte offsets.

    Doing so fixes the crashes, whilst appearing to preserve the behavior of
    -Wanalyzer-out-of-bounds in my testing.

    gcc/analyzer/ChangeLog:
            PR analyzer/110902
            PR analyzer/110928
            PR analyzer/111305
            PR analyzer/111441
            * access-diagram.cc: Include "analyzer/analyzer-selftests.h".
            (get_access_size_str): Reimplement for conversion of
            implmementation of bit_size_expr from tree to const svalue &.  Use
            svalue::maybe_print_for_user rather than tree printing routines.
            (remove_ssa_names): Make non-static.
            (bit_size_expr::get_formatted_str): Rename to...
            (bit_size_expr::maybe_get_formatted_str): ...this, adding "model"
            param and converting return type to a unique_ptr.  Update for
            conversion of implementation of bit_size_expr from tree to
            const svalue &.  Use svalue::maybe_print_for_user rather than tree
            printing routines.
            (bit_size_expr::print): Rename to...
            (bit_size_expr::maybe_print_for_user): ...this, adding "model"
            param and converting return type to bool.  Update for
            conversion of implementation of bit_size_expr from tree to
            const svalue &.  Use svalue::maybe_print_for_user rather than tree
            printing routines.
            (bit_size_expr::maybe_get_as_bytes): Add "mgr" param and convert
            return type from tree to const svalue *; reimplement.
            (access_range::access_range): Call strip_types when on
region_offset
            intializations.
            (access_range::get_size): Update for conversion of implementation
            of bit_size_expr from tree to const svalue &.
            (access_operation::get_valid_bits): Pass manager to access_range
            ctor.
            (access_operation::maybe_get_invalid_before_bits): Likewise.
            (access_operation::maybe_get_invalid_after_bits): Likewise.
            (boundaries::add): Likewise.
            (bit_to_table_map::populate): Add "mgr" param and pass it to
            access_range ctor.
            (access_diagram_impl::access_diagram_impl): Pass manager to
            bit_to_table_map::populate.
            (access_diagram_impl::maybe_add_gap): Use svalue rather than tree
            for symbolic bit offsets.  Port to new bit_size_expr
            representation.
            (access_diagram_impl::add_valid_vs_invalid_ruler): Port to new
            bit_size_expr representation.
            (selftest::assert_eq_typeless_integer): New.
            (ASSERT_EQ_TYPELESS_INTEGER): New.
            (selftest::test_bit_size_expr_to_bytes): New.
            (selftest::analyzer_access_diagram_cc_tests): New.
            * access-diagram.h (class bit_size_expr): Reimplement, converting
            implementation from tree to const svalue &.
            (access_range::access_range): Add "mgr" param.  Call strip_types
            on region_offset initializations.
            (access_range::get_size): Update decl for reimplementation.
            * analyzer-selftests.cc (selftest::run_analyzer_selftests): Call
            selftest::analyzer_access_diagram_cc_tests.
            * analyzer-selftests.h
            (selftest::analyzer_checker_script_cc_tests): Delete this stray
            typo.
            (selftest::analyzer_access_diagram_cc_tests): New decl.
            * analyzer.h (print_expr_for_user): New decl.
            (calc_symbolic_bit_offset): Update decl for reimplementation.
            (strip_types): New decls.
            (remove_ssa_names): New decl.
            * bounds-checking.cc (strip_types): New.
            (region_model::check_symbolic_bounds): Use typeless svalues.
            * region-model-manager.cc
            (region_model_manager::get_or_create_constant_svalue): Add "type"
            param.  Add overload with old signature.
            (region_model_manager::get_or_create_int_cst): Support type being
            NULL_TREE.
            (region_model_manager::maybe_fold_unaryop): Gracefully reject
folding
            of casts to NULL_TREE type.
            (get_code_for_cast): Use NOP_EXPR for "casting" svalues to
            NULL_TREE type.
            (region_model_manager::get_or_create_cast): Support "casting"
            svalues to NULL_TREE type.
            (region_model_manager::maybe_fold_binop): Don't crash on inputs
            with NULL_TREE type.  Handle folding of binops on constants with
            NULL_TREE type.  Add missing cast from PR analyzer/110902.
            Support enough folding of other ops on NULL_TREE type to support
            bounds checking.
            (region_model_manager::get_or_create_const_fn_result_svalue):
            Remove assertion that type is nonnull.
            * region-model-manager.h
            (region_model_manager::get_or_create_constant_svalue): Add
            overloaded decl taking a type.
            (region_model_manager::maybe_fold_binop): Make public.
            (region_model_manager::constants_map_t): Use
            constant_svalue::key_t for the key, rather than just tree.
            * region-model.cc (print_expr_for_user): New.
            (selftest::test_array_2): Handle casts.
            * region.cc (region_offset::calc_symbolic_bit_offset): Return
            const svalue & rather than tree, and reimplement accordingly.
            (region::calc_offset): Use ptrdiff_type_node for types of byte
            offsets.
            (region::maybe_print_for_user): New.
            (element_region::get_relative_symbolic_offset): Use NULL_TREE for
            types of bit offsets.
            (offset_region::get_bit_offset): Likewise.
            (sized_region::get_bit_size_sval): Likewise for bit sizes.
            * region.h (region::maybe_print_for_user): New decl.
            * svalue.cc (class auto_add_parens): New.
            (svalue::maybe_print_for_user): New.
            (svalue::cmp_ptr): Support typeless constant svalues.
            (tristate_from_boolean_tree_node): New, taken from...
            (constant_svalue::eval_condition): ...here.  Handle comparison of
            typeless integer svalue constants.
            * svalue.h (svalue::maybe_print_for_user): New decl.
            (class constant_svalue): Support the type of the svalue being
            NULL_TREE.
            (struct default_hash_traits<constant_svalue::key_t>): New.

    gcc/ChangeLog:
            PR analyzer/110902
            PR analyzer/110928
            PR analyzer/111305
            PR analyzer/111441
            * selftest.h (ASSERT_NE_AT): New macro.

    gcc/testsuite/ChangeLog:
            PR analyzer/110902
            PR analyzer/110928
            PR analyzer/111305
            PR analyzer/111441
            * c-c++-common/analyzer/out-of-bounds-const-fn.c: New test.
            * c-c++-common/analyzer/out-of-bounds-diagram-11.c: Update
            expected diagram output.
            * c-c++-common/analyzer/out-of-bounds-diagram-pr110928.c: New test.
            * c-c++-common/analyzer/out-of-bounds-diagram-pr111305.c: New test.
            * c-c++-common/analyzer/out-of-bounds-diagram-pr111441.c: New test.

    Signed-off-by: David Malcolm <dmalcolm@redhat.com>

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds false postive

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

David Malcolm <dmalcolm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P2                          |P3
            Summary|[13/14 Regression] GCC      |[13/14 Regression] GCC
                   |Static Analyzer             |Static Analyzer
                   |-Wanalyzer-out-of-bounds FP |-Wanalyzer-out-of-bounds
                   |and ICE problem             |false postive

--- Comment #4 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
ICE should be fixed by the above patch.

False positive still not fixed.

[Bug analyzer/111305] [13/14 Regression] GCC Static Analyzer -Wanalyzer-out-of-bounds false postive

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111305

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2