analyzer: complain about tainted sizes with "access" attribute [PR103940]
GCC 10 gained the "access" function and type attribute, which
optionally can take a size-index param:
https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
-fanalyzer in trunk (for GCC 12) has gained a -Wanalyzer-tainted-size to
complain about attacker-controlled size values, but this was only being
used deep inside the region-model code when handling the hardcoded known
behavior of certain functions (memset, IIRC).
This patch extends -Wanalyzer-tainted-size to also complain about
unsanitized attacker-controlled values being passed to function
parameters marked as a size via the "access" attribute.
Note that -fanalyzer-checker=taint is currently required in
addition to -fanalyzer to use this warning, due to scaling issues
(see bug 103533).
gcc/analyzer/ChangeLog:
PR analyzer/103940
* engine.cc (impl_sm_context::impl_sm_context): Add
"unknown_side_effects" param and use it to initialize
new m_unknown_side_effects field.
(impl_sm_context::unknown_side_effects_p): New.
(impl_sm_context::m_unknown_side_effects): New.
(exploded_node::on_stmt): Pass unknown_side_effects to sm_ctxt
ctor.
* sm-taint.cc: Include "stringpool.h" and "attribs.h".
(tainted_size::tainted_size): Drop "dir" param.
(tainted_size::get_kind): Drop "FINAL".
(tainted_size::emit): Likewise.
(tainted_size::m_dir): Drop unused field.
(class tainted_access_attrib_size): New subclass.
(taint_state_machine::on_stmt): Call check_for_tainted_size_arg on
external functions with unknown side effects.
(taint_state_machine::check_for_tainted_size_arg): New.
(region_model::check_region_for_taint): Drop "dir" param from
tainted_size ctor.
* sm.h (sm_context::unknown_side_effects_p): New.
gcc/testsuite/ChangeLog:
PR analyzer/103940
* gcc.dg/analyzer/taint-size-access-attr-1.c: New test.
Signed-off-by: David Malcolm <dmalcolm@redhat.com>