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From: David Malcolm <dmalcolm@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-3768] analyzer: fix "when 'strchr' returns non-NULL" message Date: Tue, 8 Nov 2022 02:53:53 +0000 (GMT) [thread overview] Message-ID: <20221108025353.5387F3858418@sourceware.org> (raw) https://gcc.gnu.org/g:55e042407ef307764cb9d5a4a06954518e2112b4 commit r13-3768-g55e042407ef307764cb9d5a4a06954518e2112b4 Author: David Malcolm <dmalcolm@redhat.com> Date: Mon Nov 7 21:52:30 2022 -0500 analyzer: fix "when 'strchr' returns non-NULL" message Tweak analyzer handling of strchr, so that we show the when 'strchr' returns non-NULL message for that execution path. gcc/analyzer/ChangeLog: * region-model-impl-calls.cc (region_model::impl_call_strchr): Move to on_call_post. Handle both outcomes using bifurcation, rather than just the "not found" case. * region-model.cc (region_model::on_call_pre): Move BUILT_IN_STRCHR and "strchr" to... (region_model::on_call_post): ...here. gcc/testsuite/ChangeLog: * gcc.dg/analyzer/strchr-1.c (test_literal): Detect writing to a string literal. Verify that we emit the "when '__builtin_strchr' returns non-NULL" message. Signed-off-by: David Malcolm <dmalcolm@redhat.com> Diff: --- gcc/analyzer/region-model-impl-calls.cc | 14 +++++++------- gcc/analyzer/region-model.cc | 14 ++++++++++++-- gcc/testsuite/gcc.dg/analyzer/strchr-1.c | 3 ++- 3 files changed, 21 insertions(+), 10 deletions(-) diff --git a/gcc/analyzer/region-model-impl-calls.cc b/gcc/analyzer/region-model-impl-calls.cc index 30fa765c4b4..46dbbb53bdc 100644 --- a/gcc/analyzer/region-model-impl-calls.cc +++ b/gcc/analyzer/region-model-impl-calls.cc @@ -1013,7 +1013,7 @@ region_model::impl_call_realloc (const call_details &cd) } } -/* Handle the on_call_pre part of "strchr" and "__builtin_strchr". */ +/* Handle the on_call_post part of "strchr" and "__builtin_strchr". */ void region_model::impl_call_strchr (const call_details &cd) @@ -1075,13 +1075,13 @@ region_model::impl_call_strchr (const call_details &cd) bool m_found; }; - /* Bifurcate state, creating a "not found" out-edge. */ + /* Body of region_model::impl_call_strchr. */ if (cd.get_ctxt ()) - cd.get_ctxt ()->bifurcate (make_unique<strchr_call_info> (cd, false)); - - /* The "unbifurcated" state is the "found" case. */ - strchr_call_info found (cd, true); - found.update_model (this, NULL, cd.get_ctxt ()); + { + cd.get_ctxt ()->bifurcate (make_unique<strchr_call_info> (cd, false)); + cd.get_ctxt ()->bifurcate (make_unique<strchr_call_info> (cd, true)); + cd.get_ctxt ()->terminate_path (); + } } /* Handle the on_call_pre part of "strcpy" and "__builtin_strcpy_chk". */ diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc index edf3412a817..e182d2e0e1a 100644 --- a/gcc/analyzer/region-model.cc +++ b/gcc/analyzer/region-model.cc @@ -2223,7 +2223,7 @@ region_model::on_call_pre (const gcall *call, region_model_context *ctxt, case BUILT_IN_REALLOC: return false; case BUILT_IN_STRCHR: - impl_call_strchr (cd); + /* Handle in "on_call_post". */ return false; case BUILT_IN_STRCPY: case BUILT_IN_STRCPY_CHK: @@ -2341,7 +2341,7 @@ region_model::on_call_pre (const gcall *call, region_model_context *ctxt, else if (is_named_call_p (callee_fndecl, "strchr", call, 2) && POINTER_TYPE_P (cd.get_arg_type (0))) { - impl_call_strchr (cd); + /* Handle in "on_call_post". */ return false; } else if (is_named_call_p (callee_fndecl, "strlen", call, 1) @@ -2418,6 +2418,12 @@ region_model::on_call_post (const gcall *call, impl_call_pipe (cd); return; } + else if (is_named_call_p (callee_fndecl, "strchr", call, 2) + && POINTER_TYPE_P (cd.get_arg_type (0))) + { + impl_call_strchr (cd); + return; + } /* Was this fndecl referenced by __attribute__((malloc(FOO)))? */ if (lookup_attribute ("*dealloc", DECL_ATTRIBUTES (callee_fndecl))) @@ -2435,6 +2441,10 @@ region_model::on_call_post (const gcall *call, impl_call_realloc (cd); return; + case BUILT_IN_STRCHR: + impl_call_strchr (cd); + return; + case BUILT_IN_VA_END: impl_call_va_end (cd); return; diff --git a/gcc/testsuite/gcc.dg/analyzer/strchr-1.c b/gcc/testsuite/gcc.dg/analyzer/strchr-1.c index dfe1bc9ea1a..bfa48916ca2 100644 --- a/gcc/testsuite/gcc.dg/analyzer/strchr-1.c +++ b/gcc/testsuite/gcc.dg/analyzer/strchr-1.c @@ -3,12 +3,13 @@ const char* test_literal (int x) { - char *p = __builtin_strchr ("123", x); + char *p = __builtin_strchr ("123", x); /* { dg-message "when '__builtin_strchr' returns non-NULL" } */ if (p) { __analyzer_eval (*p == x); /* { dg-message "UNKNOWN" } */ /* TODO: this ought to be TRUE, but it's unclear that it's worth stashing this constraint. */ + *p = 'A'; /* { dg-warning "write to string literal" } */ } return p; }
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