https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106235
--- Comment #3 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:d777b38cde91a87f2345dcd13901862a9513562a commit r13-3947-gd777b38cde91a87f2345dcd13901862a9513562a Author: David Malcolm <dmalc...@redhat.com> Date: Sun Nov 13 17:53:23 2022 -0500 analyzer: new warning: -Wanalyzer-tainted-assertion [PR106235] This patch adds a new -Wanalyzer-tainted-assertion warning to -fanalyzer's "taint" mode (which also requires -fanalyzer-checker=taint). It complains about attacker-controlled values being used in assertions, or in any expression affecting control flow that guards a "noreturn" function. As noted in the docs part of the patch, in such cases: - when assertion-checking is enabled: an attacker could trigger a denial of service by injecting an assertion failure - when assertion-checking is disabled, such as by defining NDEBUG, an attacker could inject data that subverts the process, since it presumably violates a precondition that is being assumed by the code. For example, given: #include <assert.h> int __attribute__((tainted_args)) test_tainted_assert (int n) { assert (n > 0); return n * n; } compiling with -fanalyzer -fanalyzer-checker=taint gives: t.c: In function 'test_tainted_assert': t.c:6:3: warning: use of attacked-controlled value in condition for assertion [CWE-617] [-Wanalyzer-tainted-assertion] 6 | assert (n > 0); | ^~~~~~ 'test_tainted_assert': event 1 | | 4 | test_tainted_assert (int n) | | ^~~~~~~~~~~~~~~~~~~ | | | | | (1) function 'test_tainted_assert' marked with '__attribute__((tainted_args))' | +--> 'test_tainted_assert': event 2 | | 4 | test_tainted_assert (int n) | | ^~~~~~~~~~~~~~~~~~~ | | | | | (2) entry to 'test_tainted_assert' | 'test_tainted_assert': events 3-6 | |/usr/include/assert.h:106:10: | 106 | if (expr) \ | | ^ | | | | | (3) use of attacker-controlled value for control flow | | (4) following 'false' branch (when 'n <= 0')... |...... | 109 | __assert_fail (#expr, __FILE__, __LINE__, __ASSERT_FUNCTION); \ | | ~~~~~~~~~~~~~ | | | | | (5) ...to here | | (6) treating '__assert_fail' as an assertion failure handler due to '__attribute__((__noreturn__))' | The testcases have various examples for BUG and BUG_ON from the Linux kernel; there, the diagnostic treats "panic" as an assertion failure handler, due to '__attribute__((__noreturn__))'. gcc/analyzer/ChangeLog: PR analyzer/106235 * analyzer.opt (Wanalyzer-tainted-assertion): New. * checker-path.cc (checker_path::fixup_locations): Pass false to pending_diagnostic::fixup_location. * diagnostic-manager.cc (get_emission_location): Pass true to pending_diagnostic::fixup_location. * pending-diagnostic.cc (pending_diagnostic::fixup_location): Add bool param. * pending-diagnostic.h (pending_diagnostic::fixup_location): Add bool param to decl. * sm-taint.cc (taint_state_machine::m_tainted_control_flow): New. (taint_diagnostic::describe_state_change): Drop "final". (class tainted_assertion): New. (taint_state_machine::taint_state_machine): Initialize m_tainted_control_flow. (taint_state_machine::alt_get_inherited_state): Support comparisons being tainted, based on their arguments. (is_assertion_failure_handler_p): New. (taint_state_machine::on_stmt): Complain about calls to assertion failure handlers guarded by an attacker-controller conditional. Detect attacker-controlled gcond conditionals and gswitch index values. (taint_state_machine::check_control_flow_arg_for_taint): New. gcc/ChangeLog: PR analyzer/106235 * doc/gcc/gcc-command-options/option-summary.rst: Add -Wno-analyzer-tainted-assertion. * doc/gcc/gcc-command-options/options-that-control-static-analysis.rst: Add -Wno-analyzer-tainted-assertion. gcc/testsuite/ChangeLog: PR analyzer/106235 * gcc.dg/analyzer/taint-assert-BUG_ON.c: New test. * gcc.dg/analyzer/taint-assert-macro-expansion.c: New test. * gcc.dg/analyzer/taint-assert.c: New test. * gcc.dg/analyzer/taint-assert-system-header.c: New test. * gcc.dg/analyzer/test-assert.h: New header. * gcc.dg/plugin/analyzer_gil_plugin.c (gil_diagnostic::fixup_location): Add bool param. Signed-off-by: David Malcolm <dmalc...@redhat.com>
