From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 82329385B503; Fri, 19 Jul 2024 16:48:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 82329385B503
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1721407723;
	bh=gza10TJa7ccT+ajypnxEfeiJKz7DUZDX7lPZ/Z3QIRM=;
	h=From:To:Subject:Date:From;
	b=hEuMHItu1JjEe5WU3Xjvl8smhnsLVe9ilOVL0Jq4hcC+3iA5gh+A9tTih8LlYg9Sm
	 eS3nxz2RhZAmShfTh6+G/Z2mmERnf0a7ppJDNzwws4GkXdBT019apmquTbE0Y7nLMa
	 sTJcB7rTpxMbYA6wb89D5tCEeK7QKsFOTHFk2ma4=
From: "dmalcolm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug analyzer/116006] New: RFE: detect usage of pointers to local
 variables that are out of scope
Date: Fri, 19 Jul 2024 16:48:43 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: analyzer
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: dmalcolm at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: dmalcolm at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-116006-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D116006

            Bug ID: 116006
           Summary: RFE: detect usage of pointers to local variables that
                    are out of scope
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: dmalcolm at gcc dot gnu.org
  Target Milestone: ---

Consider e.g.:

struct A *extref =3D something;
...
for (int i =3D 0; i < n; i++)
{
        struct A intref =3D *extref;
        intref.memb =3D i;
        extref =3D &intref;
}

This is storing a pointer to local variable "intref" into extref.

I think we detect the case where someone tries to use *extref once the func=
tion
frame has been popped (via the poisoned_svalue machinery) but I don't think=
 we
detect the case where the usage happens in the same function but outside the
scope of "intref".

Trying it out here: https://godbolt.org/z/6s9WMh53K but I can't seem to tri=
gger
even the popped frame case=